Methods and devices for tissue grasping and assessment

ABSTRACT

Devices, systems and methods are provided for stabilizing and grasping tissues such as valve leaflets, assessing the grasp of these tissues, approximating and fixating the tissues, and assessing the fixation of the tissues to treat cardiac valve regurgitation, particularly mitral valve regurgitation.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 14/070,936, filed Nov. 4, 2013, which is a continuation of U.S.patent application Ser. No. 13/239,514, filed Sep. 22, 2011, nowabandoned, which is a continuation of U.S. patent application Ser. No.12/575,100, now U.S. Pat. No. 8,052,592, filed Oct. 7, 2009, which is adivisional of U.S. patent application Ser. No. 11/237,213, now U.S. Pat.No. 7,635,329, filed Sep. 27, 2005 which claims the benefit and priorityof U.S. Provisional Patent Application No. 60/613,867, filed Sep. 27,2004, the full disclosures of which are hereby incorporated byreference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates generally to medical methods, devices, andsystems. In particular, the present invention relates to methods,devices, and systems for the endovascular, percutaneous or minimallyinvasive surgical treatment of bodily tissues, such as tissueapproximation or valve repair. More particularly, the present inventionrelates to repair of valves of the heart and venous valves.

Surgical repair of bodily tissues often involves tissue approximationand fastening of such tissues in the approximated arrangement. Whenrepairing valves, tissue approximation includes coapting the leaflets ofthe valves in a therapeutic arrangement which may then be maintained byfastening or fixing the leaflets. Such coaptation can be used to treatregurgitation which most commonly occurs in the mitral valve.

Mitral valve regurgitation is characterized by retrograde flow from theleft ventricle of a heart through an incompetent mitral valve into theleft atrium. During a normal cycle of heart contraction (systole), themitral valve acts as a check valve to prevent flow of oxygenated bloodback into the left atrium. In this way, the oxygenated blood is pumpedinto the aorta through the aortic valve. Regurgitation of the valve cansignificantly decrease the pumping efficiency of the heart, placing thepatient at risk of severe, progressive heart failure.

Mitral valve regurgitation can result from a number of differentmechanical defects in the mitral valve or the left ventricular wall. Thevalve leaflets, the valve chordae which connect the leaflets to thepapillary muscles, the papillary muscles or the left ventricular wallmay be damaged or otherwise dysfunctional. Commonly, the valve annulusmay be damaged, dilated, or weakened limiting the ability of the mitralvalve to close adequately against the high pressures of the leftventricle.

The most common treatments for mitral valve regurgitation rely on valvereplacement or repair including leaflet and annulus remodeling, thelatter generally referred to as valve annuloplasty. A recent techniquefor mitral valve repair which relies on suturing adjacent segments ofthe opposed valve leaflets together is referred to as the “bow-tie” or“edge-to-edge” technique. While all these techniques can be veryeffective, they usually rely on open heart surgery where the patient'schest is opened, typically via a sternotomy, and the patient placed oncardiopulmonary bypass. The need to both open the chest and place thepatient on bypass is traumatic and has associated high mortality andmorbidity.

Consequently, alternative and additional methods, devices, and systemsfor performing the repair of mitral and other cardiac valves have beendeveloped. Such methods, devices, and systems preferably do not requireopen chest access and are capable of being performed eitherendovascularly, i.e., using devices which are advanced to the heart froma point in the patient's vasculature remote from the heart or by aminimally invasive approach. Examples of such methods, devices andsystems are provided in U.S. Pat. Nos. 6,629,534, 6,752,813, and U.S.patent application Ser. Nos. 10/441,753, 10/441,531, 11/130,818,10/441,508, 10/441,687, 10/975,555, all of which are incorporated hereinby reference for all purposes.

In some instances, however, a variety of challenges are faced indesirably fixating the valve leaflets. For example, it is commonly foundin cases of mitral valve regurgitation that a portion of the leaflet ismoving out of phase with the other leaflets or portions of the leaflets.This can occur due to an elongation or disconnection of the structures(chordae tendinae) holding the leaflets stable and in synchrony. Such amalfunction can lead to one leaflet or portion of a leaflet to swing or“flail” above the level of healthy coaptation, thereby allowing blood toregurgitate into the right atrium. Such flailing provides a challenge tothe practitioner when attempting to fix the leaflets together,particularly via an endoscopic approach. The leaflets may be difficultto grasp, and even when grasped, the leaflets may not be desirablygrasped. For example, a leaflet may only be partially grasped ratherthan having full contact with a grasping element. This may lead to lessdesirable coaptation and/or eventual slippage of the leaflet fromfixation.

Therefore, devices, systems and methods are desired which stabilize thetissue, to resist flailing and other movement, prior to and/or duringgrasping of the tissue. Further, devices, systems and methods aredesired which assist in grasping the tissue, enable more desirablecoaptation of tissues, provide grasping assessment, and enable thepractitioner to determine if desirable grasping of the tissues hasoccurred, particularly prior to fixation. And still further, devices,systems and methods are desired which enable fixation assessment,enabling the practitioner to determine if desirable fixation of thetissues has occurred. These would be useful for repair of tissues in thebody other than leaflets and other than heart valves. At least some ofthese objectives will be met by the inventions described hereinbelow.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a variety of devices, systems and methodsfor stabilizing, grasping, assessing and fixating tissues, particularlyvalve leaflets in the treatment of cardiac valve regurgitation, moreparticularly mitral valve regurgitation. Many of the devices, systemsand methods utilize or are utilized in conjunction with a preferredembodiment of a fixation device having at least one proximal element andat least one distal element, wherein the tissue is grasped therebetween.It may be appreciated, however, that the devices, systems and methods ofthe present invention may utilize any suitable device, particularly anyminimally invasive device. When treating valve leaflets, the leafletsare typically grasped to position the fixation device along the line ofcoaptation at a location which reduces regurgitation of the valve, suchas near the center of the valve simulating a standard surgical bow-tierepair. However, more than one fixation device may be placed, and invarious arrangements, as will be discussed in later sections.

To assist in desirable grasping of the tissue, a variety of devices andtechniques are provided to stabilize the tissue prior to grasping. Suchstabilization is aimed to assist in effectively and efficiently graspingthe tissue thereby increasing the likelihood that the desired amount oftissue will be incorporated into the fixation device withoutnecessitating multiple grasps. Further, a variety of devices andtechniques are provided to improve a grasp, such as by adjusting theposition of the grasped tissue between the proximal and distal elements.Once the tissue or leaflets have been grasped, it is often desired toevaluate or assess the quality of the grasp, such as the amount ofpurchase, orientation of the tissues and likelihood that the fixationdevice will maintain the grasp over time. Thus, a variety of devices andtechniques are provided to assess the quality of the grasp. Further,once the tissue has been fixed by the fixation device, the quality ofthe fixation of the tissue may be evaluated or assessed. This can beachieved by evaluating the improvement in the medical condition beingtreated, such as improvement in regurgitation. It is often desired toassess the fixation prior to decoupling the fixation device from thedelivery catheter so that the fixation device may be repositioned if theimprovement is not satisfactory. Thus, a variety of devices andtechniques are provided to assess the fixation prior to decoupling thefixation devices. Additional devices, systems and methods are alsoprovided.

In one aspect of the present invention, methods are provided forassessing the grasp of one or more tissues by a minimally invasivedevice. In one embodiment, the method includes advancing a minimallyinvasive device having a proximal element and a distal element into abody cavity having a tissue, grasping the tissue between the proximalelement and the distal element and assessing the presence of the tissuein a target area between the proximal and distal elements. Typically,the tissue comprises valve leaflets. In some embodiments, assessing thepresence comprises observing the target area under fluoroscopy,ultrasound or echocardiography. In such instances, the method mayfurther comprise enhancing the visibility of at least a portion of theproximal element and/or the distal element. Alternatively or inaddition, the method may further comprise enhancing the visibility ofthe tissue.

In a variety of embodiments, the device includes an indicator whichindicates the presence of tissue within the target area. In suchinstances, the method may further comprise observing the indicator. Whenthe indicator changes shape and/or orientation based on the presence oftissue within the target area, observing the indicator may includeobserving the change in shape and/or orientation.

In some embodiments, the device includes an injectable enhancedvisibility substance. In such instances, assessing the presence oftissue in the target area may comprise observing a flow pattern of theenhanced visibility substance. When the substance is contained in areservoir having ports, assessing the presence of tissue in the targetarea may comprise observing the substance flowing through ports near thetarget area.

In further embodiments, the method further comprising introducing aninjectable enhanced visibility substance through the device. In suchinstances, assessing the presence of tissue in the target area maycomprise observing the absence of a flow pattern of the enhancedvisibility substance. In still further embodiments, the method furtherincludes advancing a probe into the target area. In such instances,assessing the presence of the tissue in a target area may comprisedetermining a depth of the probe advancement. In some embodiments, thedevice includes a sensor which indicates the presence of tissue withinthe target area, wherein the method further comprises evaluating asignal from the sensor.

In another aspect of the present invention, methods are provided foradjusting the tissue grasped between the proximal and distal element. Insome embodiments, the method comprises advancing a minimally invasivedevice having a proximal element and a distal element into a body cavityhaving a tissue, grasping the tissue between the proximal element andthe distal element, and adjusting the tissue between the proximalelement and the distal element. Adjusting may comprise applying suctionto the tissue and moving the tissue by suction forces. When the deviceincludes a secondary grasper, adjusting may comprise grasping and movingthe tissue with the secondary grasper. When the device includes arotating component which moves the tissue between the proximal anddistal elements, adjusting may comprise rotating the rotating component.When the proximal element is moveable relative to the distal element,adjusting may comprise moving the proximal element relative to thedistal element. Typically, the tissue comprises valve leaflets.

In another aspect of the present invention, methods are provided fortemporarily stabilizing valve leaflets. In some embodiments, the methodincludes advancing a minimally invasive device into a chamber of a hearthaving a valve with valve leaflets, temporarily stabilizing the valveleaflets by reducing movement of the valve leaflets. When the chambercomprises the left atrium, the valve comprises the mitral valve, and thedevice includes a stabilizer, temporarily stabilizing may comprisepositioning the stabilizer against the atrial side of the leaflets so asto reduce flail of the leaflets. In some embodiments, the stabilizercomprises an expandable member, a flap or at least one loop. When thedevice includes at least one loop, temporarily stabilizing may comprisespositioning the at least one loop against the leaflets so as to reducemovement of the leaflets. In some embodiments, temporarily stabilizingfurther comprises moving the at least one loop along the leaflets towardthe center of the valve so as to reduce movement of the leaflets. Whenthe chamber comprises a ventricle including chordae extending from theventricle to the valve leaflets, temporarily stabilizing may compriseholding the chordae with the device so as to reduce movement of thevalve leaflets. When the device includes an expandable member, holdingthe chordae may comprise expanding the expandable member against thechordae. In some embodiments, temporarily stabilizing the valve leafletscomprises temporarily slowing the natural pace of the heart with apacing instrument.

In a further aspect of the invention, a minimally invasive device isprovided comprising at least one proximal element and at least onedistal element configured for grasping tissue therebetween, and anindicator which indicates a presence or absence of tissue in a targetarea between the at least one proximal and distal elements. In someembodiments, the indicator comprises an enhanced visibility substance.For example, the enhanced visibility substance may be disposed on orwithin the at least one proximal and/or the at least one distalelements. The device may further comprise a reservoir within which theenhanced visibility substance is disposed. In some embodiments, thereservoir is configured to release at least a portion of the enhancedvisibility substance due to the presence of tissue in the target areabetween the at least one proximal and distal elements. Alternatively orin addition, the reservoir may be configured to move locations due tothe presence of tissue in the target area between the at least oneproximal and distal elements. Or, the device may further comprise aconduit through which the enhanced visibility substance is injectabletoward the target area.

In some embodiments, the indicator is configured to change shape and/ororientation based on a presence of tissue within the target area. Forexample, the indicator may be configured to extend into the target areain the absence of tissue within the target area and to change shape ororientation within the target area due to the presence of tissue withinthe target area. In some instances, the indicator comprises a floatingblock, a flap, a reservoir, a loop, a slackline, a probe, a detectableelement, or a combination of any of these.

In other embodiments, the indicator comprises a sensor. Examples ofsensors include a conductor, a strain gauge, a radiosensor, an opticalsensor, an ultrasound sensor, a magnetic sensor, an electricalresistance sensor, an infrared sensor, an intravascular ultrasoundsensor, a pressure sensor or a combination of any of these. Optionally,the indicator may be configured to contact the at least one distalelement forming a closed circuit when the tissue is absent within thetarget area.

In another aspect of the present invention, a minimally invasive deviceis provided comprising at least one proximal element and at least onedistal element configured for grasping tissue therebetween, and anadjustment element configured to adjust a position of the tissue betweenthe at least one proximal and distal elements. In some embodiments, theadjustment element comprises a vacuum line configured to apply suctionto the tissue to adjust the position of the tissue between the at leastone proximal and distal elements. In other embodiments, the adjustmentelement comprises a secondary grasper configured to grasp the tissue toadjust the position of the tissue between the at least one proximal anddistal elements. In still other embodiments, the adjustment elementcomprises a rotating component configured to move the tissue between theat least one proximal and distal elements. And, in yet otherembodiments, the adjustment element is configured to adjust a positionof the at least one proximal element so as to move the tissue inrelation to the at least one distal element.

In a further aspect of the present invention, a minimally invasivedevice is provided comprising at least one proximal element and at leastone distal element configured for grasping tissue therebetween, and astabilizer configured to reduce movement of the tissue prior to graspingthe tissue between the at least one proximal and distal elements. Whenthe tissue comprises a leaflet of a mitral valve, the stabilizer maycomprise an expandable member, a flap, an overtube or at least one loopconfigured to be positioned against an atrial side of the leaflets so asto reduce flail of the leaflets. For example, the stabilizer maycomprise at least one loop which is moveable toward a center of thevalve so as to reduce movement of the leaflet. When the tissue comprisesa leaflet having chordae extending therefrom, the stabilizer maycomprise an expandable member configured to hold the chordae uponexpansion so as to reduce movement of the leaflet.

In another aspect of the present invention, a system is provided forassessing quality of fixation of a tissue within a body comprising afixation device having at least one proximal element and at least onedistal element configured for grasping tissue therebetween, a catheterhaving a proximal end, a distal end and a lumen therethrough, thecatheter configured for endoluminal advancement through at least aportion of the body to the tissue, and a shaft removably coupled to thefixation device. The shaft is configured to pass through the lumen ofthe catheter, and at least a portion of the shaft is flexible to allowmovement of the fixation device relative to the catheter while thetissue is grasped between the at least one proximal element and the atleast one distal element. In some embodiments, the shaft comprises acompression coil. Thus, the system may further include a centeractuation wire configured to extend through the compression coil so asto rigidify the coil during placement of the fixation device.Optionally, the system may include a sheath extendable over at least aportion of the flexible shaft so as to rigidify the shaft duringplacement of the fixation device. Such rigidifying elements are thenremoved to allow movement of the fixation device while the tissue isgrasped to evaluate the desirability of the fixation.

In another aspect of the present invention, a method of fixing a pair ofvalve leaflets together along their coaptation line is provided. Themethod comprises fixing the pair of valve leaflets together at a firstlocation along the coaptation line with a first fixation device, andfixing the pair of valve leaflets together at a second location alongthe coaptation line with a second fixation device, wherein the first andsecond locations differ. In some embodiments, the first and secondlocations are adjacent to each other. Or, the first and second locationsmay be spaced apart, such as approximately 1 cm apart. The first andsecond locations may be positioned so as to provide a single orifice,double orifice or triple orifice geometry, to name a few, when apressure gradient opens the pair of valve leaflets.

In some embodiments, the first fixation device has a first pair ofgrasping elements and a second pair of grasping elements. Thus, fixingthe pair of valve leaflets together at the first location may comprisegrasping one leaflet of the pair of valve leaflets between the firstpair of grasping elements and grasping another leaflet of the pair ofvalve leaflets between the second pair of grasping elements. And, fixingthe pair of valve leaflets together at the second location may comprisegrasping one leaflet of the pair of valve leaflets between the firstpair of grasping elements of the second fixation device and graspinganother leaflet of the pair of valve leaflets between the second pair ofgrasping elements of the second fixation device. In some embodiments,the method further comprises assessing performance of the valve leafletsafter the step of fixing the pair of valve leaflets together at thefirst location to determine need for the step of fixing the pair ofvalve leaflets together at the second location.

Other objects and advantages of the present invention will becomeapparent from the detailed description to follow, together with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C illustrate grasping of the leaflets with a fixation device,inversion of the distal elements of the fixation device and removal ofthe fixation device, respectively.

FIG. 2A-2E illustrate example positions of fixation devices in desiredorientations relative to the leaflets.

FIGS. 3, 4A-4B, 5A-5B, 6A-6B, 7A-7B illustrate an embodiment of afixation device in various positions.

FIGS. 8A-8L, 9A-9B, 10A-10B, 11A-11B illustrate embodiments of deviceswhich stabilize the valve leaflets by reducing upward mobility andflailing of the leaflets.

FIGS. 12A-12B illustrate an embodiments which stabilizes the valveleaflets by applying tension to the chordae attached to the leaflets.

FIG. 13 illustrates a pacing lead extending to the sinoatrial node whichregulates movement of leaflets to assist in grasping of the leaflets.

FIG. 14 illustrates pacing of the left ventricle directly with a pacingcatheter.

FIG. 15 illustrates an embodiment of a fixation device having a vacuumline.

FIG. 16, illustrates an embodiment of a fixation device having anadjunct-grasper.

FIG. 17 illustrates an embodiment of a fixation device having a conveyorbelt.

FIGS. 18A-18B illustrates an embodiment of a fixation device havingproximal elements which are adjustable inwardly to draw grasped tissuefurther into the fixation device.

FIGS. 19A-19C illustrate an embodiment of a fixation device adapted foruse with a pre-grasper.

FIG. 20 illustrates a fixation device advanced via an atrial approachand a pre-grasper advanced via a ventricular approach.

FIGS. 21A-21B illustrate embodiments of a fixation device having twosingle-sided fixation elements joinable by a tether.

FIG. 22 illustrates an embodiment of fixation device havingself-engaging distal elements.

FIG. 23 illustrates an embodiment of a fixation device having suction tomaintain leaflet position after grasping.

FIGS. 24A-24B illustrate an embodiment of a fixation device havingextended frictional accessories.

FIGS. 25A-25B illustrate an embodiment of a fixation device having atextured gripping surface.

FIG. 26A-26B illustrate an embodiment of a fixation device having agripping surface which penetrates and holds the grasped leaflets withinthe fixation device.

FIGS. 27A-27B illustrate injecting leaflets with a substance whichenhances visibility.

FIG. 28 illustrates a fixation device wherein the proximal elements anddistal elements have enhanced visibility.

FIG. 29 illustrates a fixation device wherein the position of a graspedleaflet within a fixation device may be determined based on thevisibility of frictional elements.

FIG. 30 illustrates a fixation device wherein the proximal elements arecomprised of segmental parts separated by hinges or flexible areas.

FIGS. 31A-31B, 32A-32C, 33, 34A-34B, 35, 36A-36B illustrate embodimentsof a fixation device wherein the position of a grasped tissue within afixation device is determined based on the visibility of an indicatorassociated with the distal elements.

FIGS. 37A-37B illustrate embodiments of a fixation device havingmini-grippers.

FIGS. 38A-38B illustrate an embodiment having a reservoir within thedistal elements which releases a substance

FIGS. 39A-39B illustrate an embodiment of a fixation device wherein theposition of the grasped tissue within a fixation device is determinedbased on the visibility of a released substance from a conduit.

FIGS. 40A-40B illustrate an embodiment of a fixation device having aprobe connected with an insertion depth gauge to determine if a tissuehas been desirably grasped.

FIGS. 41A-41F illustrate embodiments of fixation devices havingdetectable elements extending toward the engagement surfaces todetermine if a tissue has been desirably grasped.

FIG. 42A-42B illustrate a fixation device having at least one sensordisposed on or within a distal element.

FIG. 43 illustrate a fixation device having sensors which extend into atarget area between the proximal and distal elements.

FIGS. 44A-44B illustrate a fixation device having sensors positioned onthe shaft.

FIG. 45A-45B, 46A-46B illustrate fixation devices and methods forsimulating the resultant placement and function of a fixation devicethat has been positioned to grasp leaflets of the mitral valve.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides devices, systems and methods forstabilizing and grasping tissues such as valve leaflets, assessing thegrasp of these tissues, approximating and fixating the tissues, andassessing the fixation of the tissues to treat cardiac valveregurgitation, particularly mitral valve regurgitation.

Grasping will preferably be atraumatic providing a number of benefits.By atraumatic, it is meant that the devices and methods of the inventionmay be applied to the valve leaflets and then removed without causingany significant clinical impairment of leaflet structure or function.The leaflets and valve continue to function substantially the same asbefore the invention was applied. Thus, some minor penetration ordenting of the leaflets may occur using the invention while stillmeeting the definition of “atraumatic”. This enables the devices of theinvention to be applied to a diseased valve and, if desired, removed orrepositioned without having negatively affected valve function. Inaddition, it will be understood that in some cases it may be necessaryor desirable to pierce or otherwise permanently affect the leafletsduring either grasping, fixing or both. In addition, once a leaflet isgrasped, it may be desirable to further incorporate leaflet tissue toensure that the initial grasp will result in secure tissue fixation.Furthermore, it may be desirable once the leaflet is grasped to providethe user with feedback that sufficient leaflet is incorporated, and/orto provide the user an indication of the resulting placement, both priorto releasing the fixation device thereby allowing repositioning orcorrection of the placement if desired.

It may be appreciated that each the steps of stabilizing, grasping,approximating, fixating and assessing may be accomplished by a separatedevice or a plurality of steps may be accomplished by a single device.In some embodiments, all of the steps may be achieved by a singledevice. Further, in some embodiments, steps are provided by separatedevices which approach the tissue from different directions. Forexample, when treating a mitral valve, some devices may use an atrialapproach while other devices use a ventricular approach. Although anumber of embodiments are provided to achieve these results, a generaloverview of the basic features will be presented herein. Such featuresare not intended to limit the scope of the invention and are presentedwith the aim of providing a basis for descriptions of individualembodiments presented later in the application.

I. Fixation Device Overview

Many of the devices, systems and methods of the present inventionutilize or are utilized in conjunction with a preferred embodiment of afixation device described herein and in U.S. Pat. No. 6,629,534 and U.S.patent application Ser. Nos. 10/441,531, 11/130,818, 10/975,555, all ofwhich are incorporated herein by reference for all purposes. Thefixation device is provided by an interventional tool that is positionednear a desired treatment site and used to grasp the target tissue. Inendovascular applications, the interventional tool is typically aninterventional catheter. In surgical applications, the interventionaltool is typically an interventional instrument. In preferredembodiments, fixation of the grasped tissue is accomplished bymaintaining grasping with a portion of the interventional tool which isleft behind as an implant. While the invention may have a variety ofapplications for tissue approximation and fixation throughout the body,it is particularly well adapted for the repair of valves, especiallycardiac valves such as the mitral valve.

Referring to FIG. 1A, an interventional tool 10, having a deliverydevice, such as a shaft 12, and a fixation device 14, is illustratedhaving approached the mitral valve MV from the atrial side and graspedthe leaflets LF. The mitral valve may be accessed either surgically orby using endovascular techniques, and either by a retrograde approachthrough the ventricle or by an antegrade approach through the atrium, asdescribed above. For illustration purposes, an antegrade approach isdescribed.

The fixation device 14 is releasably attached to the shaft 12 of theinterventional tool 10 at its distal end. When describing the devices ofthe invention herein, “proximal” shall mean the direction toward the endof the device to be manipulated by the user outside the patient's body,and “distal” shall mean the direction toward the working end of thedevice that is positioned at the treatment site and away from the user.With respect to the mitral valve, proximal shall refer to the atrial orupstream side of the valve leaflets and distal shall refer to theventricular or downstream side of the valve leaflets.

The fixation device 14 typically comprises proximal elements 16 (orgripping elements) and distal elements 18 (or fixation elements) whichprotrude radially outward and are positionable on opposite sides of theleaflets LF as shown so as to capture or retain the leafletstherebetween. The proximal elements 16 are preferably comprised ofcobalt chromium, nitinol or stainless steel, and the distal elements 18are preferably comprised of cobalt chromium alloy (such as Elgiloy®) orstainless steel, however any suitable materials may be used. Thefixation device 14 is coupleable to the shaft 12 by a coupling mechanism17. The coupling mechanism 17 allows the fixation device 14 to detachand be left behind as an implant to hold the leaflets together in thecoapted position.

In some situations, it may be desired to reposition or remove thefixation device 14 after the proximal elements 16, distal elements 18,or both have been deployed to capture the leaflets LF. Suchrepositioning or removal may be desired for a variety of reasons, suchas to reapproach the valve in an attempt to achieve better valvefunction, more optimal positioning of the device 14 on the leaflets,better purchase on the leaflets, to detangle the device 14 fromsurrounding tissue such as chordae, to exchange the device 14 with onehaving a different design, or to abort the fixation procedure, to name afew. To facilitate repositioning or removal of the fixation device 14the distal elements 18 are releasable and optionally invertible to aconfiguration suitable for withdrawal of the device 14 from the valvewithout tangling or interfering with or damaging the chordae, leafletsor other tissue. FIG. 1B illustrates inversion wherein the distalelements 18 are moveable in the direction of arrows 40 to an invertedposition. Likewise, the proximal elements 16 may be raised, if desired.In the inverted position, the device 14 may be repositioned to a desiredorientation wherein the distal elements may then be reverted to agrasping position against the leaflets as in FIG. 1A. Alternatively, thefixation device 14 may be withdrawn (indicated by arrow 42) from theleaflets as shown in FIG. 1C. Such inversion reduces trauma to theleaflets and minimizes any entanglement of the device with surroundingtissues. Once the device 14 has been withdrawn through the valveleaflets, the proximal and distal elements may be moved to a closedposition or configuration suitable for removal from the body or forreinsertion through the mitral valve.

FIGS. 2A-2C illustrate example positions of one or more fixation devices14 in desired orientations in relation to the leaflets LF. These areshort-axis views of the mitral valve MV from the atrial side, therefore,the proximal elements 16 are shown in solid line and the distal elements18 are shown in dashed line. The proximal and distal elements 16, 18 aretypically positioned to be substantially perpendicular to the line ofcoaptation C. The devices 14 may be moved roughly along the line ofcoaptation to any desired location for fixation. The leaflets LF areheld in place so that during diastole, as shown in FIG. 2A-2C, theleaflets LF remain in position between the elements 16, 18 surrounded byopenings O which result from the diastolic pressure gradient.Advantageously, leaflets LF are coapted such that their proximal orupstream surfaces are facing each other in a vertical orientation,parallel to the direction of blood flow through mitral valve MV. Theupstream surfaces may be brought together so as to be in contact withone another or may be held slightly apart, but will preferably bemaintained in the vertical orientation in which the upstream surfacesface each other at the point of coaptation. Referring to FIG. 2A, theplacement of one fixation device near the center of the leaflets LFsimulates the double orifice geometry of a standard surgical bow-tierepair. Color Doppler echo will show if the regurgitation of the valvehas been reduced. If the resulting mitral flow pattern is satisfactory,the leaflets may be fixed together in this orientation. If the resultingcolor Doppler image shows insufficient improvement in mitralregurgitation, the interventional tool 10 may be repositioned. This maybe repeated until an optimal result is produced wherein the leaflets LFare held in place. Once the leaflets are coapted in the desiredarrangement, the fixation device 14 is then detached from the shaft 12and left behind as an implant to hold the leaflets together in thecoapted position. It may be desired to add an additional fixationelement 14′, such as illustrated in FIGS. 2B-2E. In FIG. 2B, theadditional fixation element 14′ is positioned beside the previouslyplace fixation element 14 retaining the double orifice geometry. In FIG.2C, the additional fixation element 14′ is positioned a distance, suchas up to 1 cm, from the previously placed fixation element 14 creating atriple orifice geometry. In FIG. 2D, the fixation elements 14, 14′ arepositioned adjacent to each other near a first commissure CM1. Sucharrangement creates generally a single orifice geometry by plicating onone side of the valve opening. Likewise, as shown in FIG. 2E, onefixation element 14 may be positioned near the first commissure CM1 andan additional fixation element 14′ may be positioned near a secondcommissure CM2. Such arrangement also creates generally a single orificegeometry by plicating on either side of the valve opening. Theadditional fixation element 14′ may be desired to ensure adequatefixation of the leaflets LF and/or to further reposition the leafletsLF. The additional fixation element 14′ may be added at any time duringthe procedure or at a separate procedure at a later point in time. Itmay be appreciated that any number of fixation elements 14 may bepositioned to fixate the leaflets or any other tissue, including two,three, four, five or more fixation elements 14.

FIG. 3 illustrates an embodiment of a fixation device 14. Here, thefixation device 14 is shown coupled to a shaft 12 to form aninterventional tool 10. The fixation device 14 includes a couplingmember 19 and a pair of opposed distal elements 18. The distal elements18 comprise elongate arms 53, each arm having a proximal end 52rotatably connected to the coupling member 19 and a free end 54. Thefree ends 54 have a rounded shape to minimize interference with andtrauma to surrounding tissue structures. Preferably, each free end 54defines a curvature about two axes, one being a longitudinal axis 66 ofarms 53. Thus, engagement surfaces 50 have a cupped or concave shape tosurface area in contact with tissue and to assist in grasping andholding the valve leaflets. This further allows arms 53 to nest aroundthe shaft 12 in a closed position to minimize the profile of the device.Preferably, arms 53 are at least partially cupped or curved inwardlyabout their longitudinal axes 66. Also, preferably, each free end 54defines a curvature about an axis 67 perpendicular to longitudinal axis66 of arms 53. This curvature is a reverse curvature along the mostdistal portion of the free end 54. Likewise, the longitudinal edges ofthe free ends 54 may flare outwardly. Both the reverse curvature andflaring minimize trauma to the tissue engaged therewith. Arms 53 furtherinclude a plurality of openings to enhance grip and to promote tissueingrowth following implantation.

The valve leaflets are grasped between the distal elements 18 andproximal elements 16. In some embodiments, the proximal elements 16 areflexible, resilient, and cantilevered from coupling member 19. Theproximal elements are preferably resiliently biased toward the distalelements. Each proximal element 16 is shaped and positioned to be atleast partially recessed within the concavity of the distal element 18when no tissue is present. When the fixation device 14 is in the openposition, the proximal elements 16 are shaped such that each proximalelement 16 is separated from the engagement surface 50 near the proximalend 52 of arm 53 and slopes toward the engagement surface 50 near thefree end 54 with the free end of the proximal element contactingengagement surface 50, as illustrated in FIG. 3. This shape of theproximal elements 16 accommodates valve leaflets or other tissues ofvarying thicknesses.

Proximal elements 16 may include a plurality of openings 63 andscalloped side edges 61 to increase grip on tissue. The proximalelements 16 optionally include frictional accessories, frictionalfeatures or grip-enhancing elements to assist in grasping and/or holdingthe leaflets. In preferred embodiments, the frictional accessoriescomprise barbs 60 having tapering pointed tips extending towardengagement surfaces 50. It may be appreciated that any suitablefrictional accessories may be used, such as prongs, windings, bands,barbs, grooves, channels, bumps, surface roughening, sintering,high-friction pads, coverings, coatings or a combination of these.Optionally, magnets may be present in the proximal and/or distalelements. It may be appreciated that the mating surfaces will be madefrom or will include material of opposite magnetic charge to causeattraction by magnetic force. For example, the proximal elements anddistal elements may each include magnetic material of opposite charge sothat tissue is held under constant compression between the proximal anddistal elements to facilitate faster healing and ingrowth of tissue.Also, the magnetic force may be used to draw the proximal elements 16toward the distal elements 18, in addition to or alternatively tobiasing of the proximal elements toward the distal elements. This mayassist in deployment of the proximal elements 16. In another example,the distal elements 18 each include magnetic material of opposite chargeso that tissue positioned between the distal elements 18 is heldtherebetween by magnetic force.

The fixation device 14 also includes an actuation mechanism 58. In thisembodiment, the actuation mechanism 58 comprises two link members orlegs 68, each leg 68 having a first end 70 which is rotatably joinedwith one of the distal elements 18 at a riveted joint 76 and a secondend 72 which is rotatably joined with a stud 74. The legs 68 arepreferably comprised of a rigid or semi-rigid metal or polymer such asElgiloy®, cobalt chromium or stainless steel, however any suitablematerial may be used. While in the embodiment illustrated both legs 68are pinned to stud 74 by a single rivet 78, it may be appreciated,however, that each leg 68 may be individually attached to the stud 74 bya separate rivet or pin. The stud 74 is joinable with an actuator rod 64(not shown) which extends through the shaft 12 and is axially extendableand retractable to move the stud 74 and therefore the legs 68 whichrotate the distal elements 18 between closed, open and invertedpositions. Likewise, immobilization of the stud 74 holds the legs 68 inplace and therefore holds the distal elements 18 in a desired position.The stud 74 may also be locked in place by a locking feature.

In any of the embodiments of fixation device 14 disclosed herein, it maybe desirable to provide some mobility or flexibility in distal elements18 and/or proximal elements 16 in the closed position to enable theseelements to move or flex with the opening or closing of the valveleaflets. This provides shock absorption and thereby reduces force onthe leaflets and minimizes the possibility for tearing or other traumato the leaflets. Such mobility or flexibility may be provided by using aflexible, resilient metal or polymer of appropriate thickness toconstruct the distal elements 18. Also, the locking mechanism of thefixation device (described below) may be constructed of flexiblematerials to allow some slight movement of the proximal and distalelements even when locked. Further, the distal elements 18 can beconnected to the coupling mechanism 19 or to actuation mechanism 58 by amechanism that biases the distal element into the closed position(inwardly) but permits the arms to open slightly in response to forcesexerted by the leaflets. For example, rather than being pinned at asingle point, these components may be pinned through a slot that alloweda small amount of translation of the pin in response to forces againstthe arms. A spring is used to bias the pinned component toward one endof the slot.

FIGS. 4A-4B, 5A-5B, 6A-6B, 7A-7B illustrate embodiments of the fixationdevice 14 of FIG. 3 in various possible positions during introductionand placement of the device 14 within the body to perform a therapeuticprocedure. FIG. 4A illustrates an embodiment of an interventional tool10 delivered through a catheter 86. It may be appreciated that theinterventional tool 10 may take the form of a catheter, and likewise,the catheter 86 may take the form of a guide catheter or sheath.However, in this example the terms interventional tool 10 and catheter86 will be used. The interventional tool 10 comprises a fixation device14 coupled to a shaft 12 and the fixation device 14 is shown in theclosed position. FIG. 4B illustrates a similar embodiment of thefixation device of FIG. 4A in a larger view. In the closed position, theopposed pair of distal elements 18 are positioned so that the engagementsurfaces 50 face each other. Each distal element 18 comprises anelongate arm 53 having a cupped or concave shape so that together thearms 53 surround the shaft 12 and optionally contact each other onopposite sides of the shaft. This provides a low profile for thefixation device 14 which is readily passable through the catheter 86 andthrough any anatomical structures, such as the mitral valve. Inaddition, FIG. 4B further includes an actuation mechanism 58. In thisembodiment, the actuation mechanism 58 comprises two legs 68 which areeach movably coupled to a base 69. The base 69 is joined with anactuator rod 64 which extends through the shaft 12 and is used tomanipulate the fixation device 14. In some embodiments, the actuator rod64 attaches directly to the actuation mechanism 58, particularly thebase 69. However, the actuator rod 64 may alternatively attach to a stud74 which in turn is attached to the base 69. In some embodiments, thestud 74 is threaded so that the actuator rod 64 attaches to the stud 74by a screw-type action. However, the rod 64 and stud 74 may be joined byany mechanism which is releasable to allow the fixation device 14 to bedetached from shaft 12.

FIGS. 5A-5B illustrate the fixation device 14 in the open position. Inthe open position, the distal elements 18 are rotated so that theengagement surfaces 50 face a first direction. Distal advancement of thestud 74 relative to coupling member 19 by action of the actuator rod 64applies force to the distal elements 18 which begin to rotate aroundjoints 76 due to freedom of movement in this direction. Such rotationand movement of the distal elements 18 radially outward causes rotationof the legs 68 about joints 80 so that the legs 68 are directly slightlyoutwards. The stud 74 may be advanced to any desired distancecorrelating to a desired separation of the distal elements 18. In theopen position, engagement surfaces 50 are disposed at an acute anglerelative to shaft 12, and are preferably at an angle of between 90 and180 degrees relative to each other. In one embodiment, in the openposition the free ends 54 of arms 53 have a span therebetween of about10-20 mm, usually about 12-18 mm, and preferably about 14-16 mm.

Proximal elements 16 are typically biased outwardly toward arms 53. Theproximal elements 16 may be moved inwardly toward the shaft 12 and heldagainst the shaft 12 with the aid of proximal element lines 90 which canbe in the form of sutures, wires, nitinol wire, rods, cables, polymericlines, or other suitable structures. The proximal element lines 90 maybe connected with the proximal elements 16 by threading the lines 90 ina variety of ways. When the proximal elements 16 have a loop shape, asshown in FIG. 5A, the line 90 may pass through the loop and double back.When the proximal elements 16 have an elongate solid shape, as shown inFIG. 5B, the line 90 may pass through one or more of the openings 63 inthe element 16. Further, a line loop 48 may be present on a proximalelement 16, also illustrated in FIG. 5B, through which a proximalelement line 90 may pass and double back. Such a line loop 48 may beuseful to reduce friction on proximal element line 90 or when theproximal elements 16 are solid or devoid of other loops or openingsthrough which the proximal element lines 90 may attach. A proximalelement line 90 may attach to the proximal elements 16 by detachablemeans which would allow a single line 90 to be attached to a proximalelement 16 without doubling back and would allow the single line 90 tobe detached directly from the proximal element 16 when desired. Examplesof such detachable means include hooks, snares, clips or breakablecouplings, to name a few. By applying sufficient tension to the proximalelement line 90, the detachable means may be detached from the proximalelement 16 such as by breakage of the coupling. Other mechanisms fordetachment may also be used. Similarly, a lock line 92 may be attachedand detached from a locking mechanism by similar detachable means.

In the open position, the fixation device 14 can engage the tissue whichis to be approximated or treated. This embodiment is adapted for repairof the mitral valve using an antegrade approach from the left atrium.The interventional tool 10 is advanced through the mitral valve from theleft atrium to the left ventricle. The distal elements 18 are orientedto be perpendicular to the line of coaptation and then positioned sothat the engagement surfaces 50 contact the ventricular surface of thevalve leaflets, thereby grasping the leaflets. The proximal elements 16remain on the atrial side of the valve leaflets so that the leaflets liebetween the proximal and distal elements. In this embodiment, theproximal elements 16 have frictional accessories, such as barbs 60 whichare directed toward the distal elements 18. However, neither theproximal elements 16 nor the barbs 60 contact the leaflets at this time.

The interventional tool 10 may be repeatedly manipulated to repositionthe fixation device 14 so that the leaflets are properly contacted orgrasped at a desired location. Repositioning is achieved with thefixation device in the open position. In some instances, regurgitationmay also be checked while the device 14 is in the open position. Ifregurgitation is not satisfactorily reduced, the device may berepositioned and regurgitation checked again until the desired resultsare achieved.

It may also be desired to invert the fixation device 14 to aid inrepositioning or removal of the fixation device 14. FIGS. 6A-6Billustrate the fixation device 14 in the inverted position. By furtheradvancement of stud 74 relative to coupling member 19, the distalelements 18 are further rotated so that the engagement surfaces 50 faceoutwardly and free ends 54 point distally, with each arm 53 forming anobtuse angle relative to shaft 12. The angle between arms 53 ispreferably in the range of about 270 to 360 degrees. Further advancementof the stud 74 further rotates the distal elements 18 around joints 76.This rotation and movement of the distal elements 18 radially outwardcauses rotation of the legs 68 about joints 80 so that the legs 68 arereturned toward their initial position, generally parallel to eachother. The stud 74 may be advanced to any desired distance correlatingto a desired inversion of the distal elements 18. Preferably, in thefully inverted position, the span between free ends 54 is no more thanabout 20 mm, usually less than about 16 mm, and preferably about 12-14mm. In this illustration, the proximal elements 16 remain positionedagainst the shaft 12 by exerting tension on the proximal element lines90. Thus, a relatively large space may be created between the elements16, 18 for repositioning. In addition, the inverted position allowswithdrawal of the fixation device 14 through the valve while minimizingtrauma to the leaflets. Engagement surfaces 50 provide an atraumaticsurface for deflecting tissue as the fixation device is retractedproximally. It should be further noted that barbs 60 are angled slightlyin the distal direction (away from the free ends of the proximalelements 16), reducing the risk that the barbs will catch on or laceratetissue as the fixation device is withdrawn.

Once the fixation device 14 has been positioned in a desired locationagainst the valve leaflets, the leaflets may then be captured betweenthe proximal elements 16 and the distal elements 18. FIGS. 7A-7Billustrate the fixation device 14 in such a position. Here, the proximalelements 16 are lowered toward the engagement surfaces 50 so that theleaflets are held therebetween. In FIG. 7B, the proximal elements 16 areshown to include barbs 60 which may be used to provide atraumaticgripping of the leaflets. Alternatively, larger, more sharply pointedbarbs or other penetration structures may be used to pierce the leafletsto more actively assist in holding them in place. This position issimilar to the open position of FIGS. 5A-5B, however the proximalelements 16 are now lowered toward arms 53 by releasing tension onproximal element lines 90 to compress the leaflet tissue therebetween.At any time, the proximal elements 16 may be raised and the distalelements 18 adjusted or inverted to reposition the fixation device 14,if regurgitation is not sufficiently reduced.

After the leaflets have been captured between the proximal and distalelements 16, 18 in a desired arrangement, the distal elements 18 may belocked to hold the leaflets in this position or the fixation device 14may be returned to or toward a closed position.

It may be appreciated that the fixation devices 14 of the presentinvention may have any or all of the above described functions andfeatures. For example, the fixation devices 14 may or may not bemoveable to an inverted position. Or, the fixation devices 14 may or maynot include proximal elements 16. Thus, the above described aspects ofthe fixation devices 14 are simply preferred embodiments and are notintended to limit the scope of the present invention.

II. Stabilization of Leaflets

A variety of devices and techniques are provided to stabilize theleaflets prior to grasping. Such stabilization is aimed to assist ineffectively and efficiently grasping the leaflets thereby increasing thelikelihood that the desired amount of leaflet will be incorporated intothe fixation device without necessitating multiple grasps. It may beappreciated that the stabilization devices and techniques may be used incombination with the above described fixation device or may be used withany suitable grasping and/or fixing device. Further, many of suchstabilization techniques and devices may be used to stabilize valveleaflets, or other tissues, for any purpose.

Typically in cases of mitral valve regurgitation, a portion of theleaflet LF is moving out of phase with the other leaflets or portions ofthe leaflets. This can occur due to an elongation or disconnection ofthe structures (chordae tendinae) holding the leaflets stable and insynchrony. Such a malfunction can lead to one leaflet or portion of aleaflet to swing or “flail” above the level of healthy coaptation,thereby allowing blood to regurgitate into the right atrium. FIGS.8A-8L, 9A-9B, 10A-10B illustrate embodiments of devices which stabilizethe valve leaflets by reducing upward mobility and flailing of theleaflets thereby allowing the user to more reliably grasp the targetedleaflets. In these embodiments, a catheter 86 is advanced into a leftatrium LA of a heart H, as illustrated in FIG. 8A, and a fixation device14 is advanced through the catheter 86 and through a mitral valve MVhaving leaflets LF so that at least a portion of the fixation device 14is positioned within a left ventricle LV. The valve leaflets LF areshown flailing upwards toward the left atrium LA while the fixationdevice 14 resides below the valve, within the left ventricle LV. In thisexample, the fixation device 14 resembles the fixation device describedabove in relation to FIG. 3 and includes proximal elements 16 and distalelements 18. The fixation device 14 is at least partially opened toextend the distal elements 18 radially outwardly while the proximalelements 16 remain held against the shaft 12. It is desired to engagethe leaflets LF with the distal elements 18 so that the proximalelements 16 may be lowered grasping the leaflets LF therebetween.

One or more stabilizing loops 100 may be advanced from the catheter 86and positioned against the atrial side of the leaflets LF. FIG. 8Billustrates a cross-sectional top view of an embodiment of a stabilizingloop 100. The loop 100 is shown extending radially outwardly from thecatheter 86 to form a circular shape. The diameter of the circular shapemay be varied by advancement or retraction of the loop 100 from thecatheter 86. The loop 100 may be comprised of any suitable material suchas metal, polymer, or fiber, and may have any suitable form such aswire, ribbon, links, or weave. FIG. 8C provides a side view of theembodiment shown in FIG. 8B. The circular shape of the loop 100 residesin a plane substantially perpendicular to the catheter 86. Thus, theloop 100 may be positioned along the annulus of the valve, asillustrated in FIG. 8A. In this position, the leaflets LF may stillflail upwards. Referring to FIG. 8D, the diameter of the loop 100 maythen be reduced, as indicated by arrows 102. This may be achieved bypartial retraction of the loop 100 into the catheter 86. Continualreduction of the diameter draws the loop 100 from the annulus toward thecenter of the valve. As the loop 100 travels (prior loop 100′ shown indashed line), the loop 100 restricts upward motion or flailing of theleaflets LF in a controlled manner and positions the leaflets LF foroptimal grasping between the proximal and distal elements 16, 18.

It may be appreciated that more than one loop 100 may be present tostabilize the leaflets; the loops may be concentric, adjacent to eachother, in separate planes or in any suitable arrangement. For example,FIG. 8E illustrates an embodiment having a first loop 100 a and a secondloop 100 b. The loops 100 a, 100 b function similarly to the embodimentillustrated in FIGS. 8A-8D, however, the second loop 100 b is smallerand located concentrically within the first loop 100 a. The diameters ofthe loops 100 a, 100 b may have any suitable size and the relationshipof the diameters may vary. FIG. 8F provides a side view of theembodiment shown in FIG. 8E. As shown, the circular shapes of the loops100 a, 100 b reside in a plane substantially perpendicular to thecatheter 86. Thus, the loops 100 a, 100 b may be positioned against thevalve leaflets LF to stabilize the leaflets LF. The diameter of theloops 100 a, 100 b may then be reduced, simultaneously or individually,by partial retraction of the loops 100 a, 100 b into the catheter 86.Continual reduction of the diameters draw the loops 100 a, 100 b towardthe center of the valve. Again, as the loops 100 a, 100 b travel, theloops 100 a, 100 b restrict upward motion or flailing of the leaflets LFin a controlled manner and positions the leaflets LF for optimalgrasping between the proximal and distal elements 16, 18.

FIG. 8G illustrates another embodiment having a first loop 100 a and asecond loop 100 b. However, in this embodiment, the loops 100 a, 100 bare non-concentric, each loop extending from an opposite side of thecatheter 86. The diameters of the loops 100 a, 100 b may have anysuitable size and the relationship of the diameters may vary. FIG. 8Hprovides a side view of the embodiment shown in FIG. 8G. As shown, thecircular shapes of the loops 100 a, 100 b reside in a planesubstantially perpendicular to the catheter 86. Thus, the loops 100 a,100 b may be positioned against the valve leaflets LF to stabilize theleaflets LF. FIG. 8I provides a top view of the mitral valve MV whereinthe catheter 86 is positioned above the valve MV so that the fixationdevice (not shown) may be passed through the leaflets LF. The loops 100a, 100 b are shown extended radially outwardly toward the annulus. Thediameter of the loops 100 a, 100 b may then be reduced, as indicated byarrows 102. This may be achieved by partial retraction of the loops 100a, 100 b into the catheter 86. Continual reduction of the diameter drawsthe loops 100 a, 100 b from the annulus toward the center of the valve.As the loops 100 a, 100 b travel (prior loops 100 a′, 100 b′ shown indashed line), the loops 100 a, 100 b restricts upward motion or flailingof the leaflets LF in a controlled manner and positions the leaflets LFfor optimal grasping between the proximal and distal elements 16, 18. Asshown, each loop 100 a, 100 b restricts movement of an individualleaflet LF. However, it may be appreciated that the catheter 86 may beoriented (such as at a 90 degree rotation) so that each loop 100 a, 100b contacts more than one leaflet LF.

FIG. 8J illustrates an embodiment having a single loop 100 which residesin a plane substantially parallel to the catheter 86. FIG. 8K provides aside view of the embodiment shown in FIG. 8J. The loop 100 may have anysuitable shape and diameter. Thus, the loop 100 may be positionedagainst the valve leaflets LF to stabilize the leaflets LF. FIG. 8Lprovides a top view of the mitral valve MV wherein the catheter 86 ispositioned above the valve MV so that the fixation device (not shown)may be passed through the leaflets LF. The loop 100 is shown extendedradially outwardly toward the annulus, perpendicular to the commissuresC. Such positioning restricts upward movement of the leaflets LF. Inaddition, the diameter of the loop 100 may then be reduced, as indicatedby arrows 102. This may be achieved by partial retraction of the loop100 into the catheter 86. Continual reduction of the diameter draws theloop 100 from the annulus toward the center of the valve. As the loop100 travels (prior loop 100′ shown in dashed line), the loop 100maintains restricted upward motion or flailing of the leaflets LF andpositions the leaflets LF for optimal grasping between the proximal anddistal elements 16, 18.

It may be appreciated that in any of the embodiments described above,the loops may be extended to stabilize both leaflets or may be extendedto stabilize one leaflet that is flailing. This may be achieved byorientation of the catheter 86, shape of the loop 100, amount ofextension of the loop 100 or any other method. The embodimentsillustrated in FIGS. 8G-8I are particularly suited for single leafletflailing wherein only the first loop 100 a may be present. It mayfurther be appreciated that the loops 100 may include surface treatmentsor accessories, such as rollers or grippers, to assist in stabilizationof the leaflets.

FIGS. 9A-9B illustrate another embodiment which stabilizes the valveleaflets LF by reducing upward mobility and flailing of the leaflets LF.As shown in FIG. 9A, a catheter 86 is advanced into a left atrium LA ofa heart H and a fixation device 14 is advanced through the catheter 86and through a mitral valve MV having leaflets LF so that at least aportion of the fixation device 14 is positioned within a left ventricleLV. The valve leaflets LF are shown flailing upwards toward the leftatrium LA while the fixation device 14 resides below the valve, withinthe left ventricle LV. In this example, the fixation device 14 resemblesthe fixation device described above in relation to FIG. 3 and includesproximal elements 16 and distal elements 18. The fixation device 14 isat least partially opened to extend the distal elements 18 radiallyoutwardly while the proximal elements 16 remain held against the shaft12. It is desired to engage the leaflets LF with the distal elements 18so that the proximal elements 16 may be lowered grasping the leaflets LFtherebetween.

One or more flaps 104 may extend radially outwardly from the catheter86, as shown, and be positioned against the atrial side of the leafletsLF. The flaps 104 may be comprised of any suitable material such asmetal, polymer, or fiber, and may have any suitable form such as asolid, a mesh, or a weave. Further, the flaps 104 may have any suitableshape and may include one or more cutouts 106. As shown in FIG. 9B, thecutouts 106 may be sized and positioned to allow the proximal elements16 of the fixation device 14 to extend therethrough. This allows theflaps 104 to be held against the atrial side of the leaflets LFrestricting upward motion or flailing of the leaflets LF. This positionsthe leaflets LF for optimal grasping between the proximal and distalelements 16, 18. Once the leaflets have been grasped, the flaps 104 maybe removed with the catheter 86 or may be left behind to assist inholding the leaflets LF.

FIGS. 10A-10B illustrate another embodiment which stabilizes the valveleaflets LF by reducing upward mobility and flailing of the leaflets LF.As shown in FIG. 10A, a catheter 86 is advanced into a left atrium LA ofa heart H and a fixation device 14 is advanced through the catheter 86and through a mitral valve MV having leaflets LF so that at least aportion of the fixation device 14 is positioned within a left ventricleLV. The valve leaflets LF are shown flailing upwards toward the leftatrium LA while the fixation device 14 resides below the valve, withinthe left ventricle LV. In this example, the fixation device 14 resemblesthe fixation device described above in relation to FIG. 3 and includesproximal elements 16 and distal elements 18. The fixation device 14 isat least partially opened to extend the distal elements 18 radiallyoutwardly while the proximal elements 16 remain held against the shaft12. It is desired to engage the leaflets LF with the distal elements 18so that the proximal elements 16 may be lowered grasping the leaflets LFtherebetween.

One or more expandable members 110 may extend radially outwardly fromthe catheter 86, as shown, and be positioned against the atrial side ofthe leaflets LF. The expandable member 110 may be comprised of anysuitable material such as silicone or polyurethane and may have anysuitable form such as a balloon. FIG. 10B provides an additional view ofthe embodiment. As shown, the expandable member 110 may be expandedwithin the left atrium and held against the atrial side of the leafletsLF restricting upward motion or flailing of the leaflets LF. Thispositions the leaflets LF for optimal grasping between the proximal anddistal elements 16, 18.

FIGS. 11A-11B illustrate another embodiment which stabilizes the valveleaflets LF by reducing upward mobility and flailing of the leaflets LF.In this example, the fixation device 14 resembles the fixation devicedescribed above in relation to FIG. 3 and includes proximal elements 16and distal elements 18. Again, the fixation device 14 is advancedthrough a catheter and through a mitral valve MV having leaflets LF sothat the distal elements 18 of the fixation device 14 are positionedwithin a left ventricle LV. The fixation device 14 is at least partiallyopened to extend the distal elements 18 radially outwardly while theproximal elements 16 remain held against the shaft 12. It is desired toengage the leaflets LF with the distal elements 18 so that the proximalelements 16 may then be lowered grasping the leaflets LF therebetween.However, prior to lowering the proximal elements 16, an overtube 121having slots 123 is advanced over the shaft 12 and be positioned againstthe atrial side of the leaflets LF, as illustrated in FIG. 11B. Theovertube 121 may be comprised of any suitable material such aspolyimide, poly ethyl ethyl ketone (PEEK™), nylon resins (such asPEBAX®), or polyurethane and the slots may have any suitable dimensionto allow passage of the proximal elements 16 therethrough. Holding ofthe leaflets LF by the overtube 121 restricts upward motion or flailingof the leaflets LF, and allows confirmation that leaflets are positionedcorrectly prior to lowering the proximal elements 16. This positions theleaflets LF for optimal grasping between the proximal and distalelements 16, 18. The proximal elements 16 may then be released, whereinthe proximal elements 16 pass through the slots 123 hold the leafletsbetween the proximal and distal elements 16, 18. The overtube 121 maythen be retracted and removed.

FIGS. 12A-12B illustrate embodiment which stabilizes the valve leafletsby applying tension to the chordae attached to the leaflets. Suchstabilization may be desired to reducing upward mobility and flailing ofthe leaflets or to simply reduce movement of the leaflets. FIG. 12Aillustrates a heart H having a mitral valve MV comprised of leaflets LF.Chordae CH are shown extending from one of the leaflets LF to the leftventricle LV. It may be appreciated that chordae are numerous and extendfrom both leaflets to the left ventricle however select chordae areillustrated for simplicity. As shown in FIG. 12B, a catheter 120 havingan expandable member 122, such as a balloon, may be advanced to the leftventricle

LV wherein the catheter 120 is positioned and the expandable member 122expanded so that tension is applied to the chordae CH. FIG. 12B showsthe catheter 120 advanced through the aortic valve AV however thecatheter 120 may approach the chordae CH via any suitable pathway,including through the mitral valve MV or through the septum S. Applyingtension to the chordae CH adjusts the position of the attached leafletLF. Thus, the leaflet LF may be manipulated and repositioned bymanipulating the catheter 120 and expandable member 122, includingvarying expansion of the expandable member 122. In particular, bypressing laterally against the chordae CH with the expandable member 122the leaflet LF may be drawn downward restricting upward mobility andflailing of the leaflet LF. Once the leaflets LF are disposed in adesirable position, the leaflets LF may be fixed by a fixation devicesuch as described in relation to FIG. 3. Alternatively, a grasper may beemployed to tension the chordae CH.

The above described embodiments focus on mechanically stabilizing thevalve leaflets. Additional embodiments focus on stabilizing the valveleaflets by physiologically slowing the motion of the leaflets. This maybe achieved by slowing the natural pace of the heart. In one embodiment,illustrated in FIG. 13, a pacemaker 130, or pulse generator, is shownhaving a pacing lead 132 with an electrode 134 which extend to thesinoatrial node SA in the right atrium RA. Pacing is achieved when thepacemaker 130 sends electrical impulses through the pacing lead 132 tothe electrode 134 which stimulates the sinoatrial node SA. Thisstimulates the right atrium RA to pump blood into the right ventricle RVand thereon through the heart H. Thus, the pumping of the heart andtherefore movement of the leaflets of the valves can be regulated withthe use of the pacemaker 130. FIG. 13 illustrates a fixation device 14passed through the leaflets LF of the mitral valve MV. The movement ofthe leaflets LF may be paced so that, for example, the mitral valve MVstays in systole (closed) for a longer period of time to aid in graspingthe leaflets LF with the fixation device 14. Similarly, as illustratedin FIG. 14, the left ventricle LV may be paced directly with a pacingcatheter 136 by stimulating left bundle LB. This may be achieved byadvancing the pacing catheter 136 through the aortic valve AV to theleft ventricle LV as shown.

III. Grasping Assistance

To assist in effectively and efficiently grasping the leaflets, avariety of devices and techniques are provided. Many of the devices andtechniques will be described as adjuncts to the fixation devicedescribed in relation to FIG. 3. However, many features may be used withany suitable grasping and/or fixing device. Further, many of suchtechniques and devices may be used to grasp valve leaflets, or othertissues, for any purpose.

In some situations, one or more leaflets LF are not grasped between theproximal elements 16 and distal elements 18 in a desired position. Forexample, a less than desired amount of the leaflet LF may be grasped.Such decreased purchase may, for example, reduce the effectivity of theregurgitation treatment and/or increase the risk of the leaflet LFslipping out of the fixation device. Once a portion of the leaflet LF isgrasped, the leaflet LF position may be adjusted; for example, theleaflet LF may be “pulled in” or advanced toward the shaft 12 toincrease the purchase. Embodiments to assist in such adjustment areprovided in FIGS. 15-17, 18A-18B.

FIG. 15 illustrates an embodiment of a fixation device 14 similar to thefixation device 14 illustrated in FIG. 3. As shown, a leaflet LF ispartially grasped between a proximal element 16 and a distal element 18.In this embodiment, a vacuum line 140 extends through the shaft 12 andis connected to a vacuum source 142. The vacuum line 140 has a distalend 144 which protrudes into a space 146 between the proximal and distalelement 16, 18. Actuation of the vacuum source 142 applies suction tothe space 146 which draws the leaflet LF inward toward the shaft 12.Thus, the leaflet LF, once grasped, may be repositioned within theproximal and distal elements by suction force. It may be appreciatedthat the same vacuum line 140 or an additional vacuum line may applysuction to a leaflet between the other proximal and distal elements.Further, it may be appreciated that suction force may be applied duringthe initial grasp to assist in the act of grasping.

Similarly, as illustrated in FIG. 16, another embodiment of a fixationdevice 14 is shown similar to the fixation device 14 illustrated in FIG.3. Again, a leaflet LF is partially grasped between a proximal element16 and a distal element 18. In this embodiment, an adjunct-grasperchannel 150 extends through the shaft 12 for passage of anadjunct-grasper 152 having jaws 154, however any type of graspingmechanism may be present such as atraumatic hooks, clamps or claws. Thejaws 154 protrude into a space 146 between the proximal and distalelement 16, 18. The adjunct-grasper 152 may be advanced to grasp theleaflet LF with the jaws 154 and retracted to pull the leaflet LF inwardtoward the shaft 12. Thus, the leaflet LF may be repositioned bymanipulation of the adjunct-grasper 152. It may be appreciated that thesame or an additional adjunct-grasper 152 may be used to reposition aleaflet between the other proximal and distal elements. Further, it maybe appreciated that the adjunct-grasper 152 may be used during theinitial grasp to assist in the act of grasping.

FIG. 17 illustrates another embodiment of a fixation device 14 similarto the fixation device 14 illustrated in FIG. 3. Again, a leaflet LF ispartially grasped between a proximal element 16 and a distal element 18.In this embodiment, a conveyor belt 160 is disposed within each distalelement 18 so that a surface of the belt 160 contacts the graspedleaflet LF. The conveyor belt 160 is mounted on one or more rollers 162.Rotation of the rollers 162 moves the conveyor belt 160 which in turnmoves the contacted leaflet LF. For example, clockwise rotation of therollers 162 may pull or drag the leaflet LF inwardly toward the shaft12, as shown. Similarly, counterclockwise rotation of the rollers 162may pull or drag the leaflet LF outwardly. Thus, the leaflet LF may berepositioned by movement of the conveyor belt 160. It may be appreciatedthat conveyor belts 160 disposed within the distal elements 18 mayfunction independently or in unison. Further, it may be appreciated thatthe conveyor belts 160 may be used during the initial grasp to assist inthe act of grasping.

FIGS. 18A-18B illustrate another embodiment of a fixation device 14similar to the fixation device 14 illustrated in FIG. 3 having proximalelements 16 and distal elements 18. In this embodiment, the proximalelements 16 are connected by a bridge 166 which straddles the shaft 12.Referring to FIG. 18B, once a leaflet is grasped between the proximaland distal elements 16, 18, a force may be applied to move the bridge166 toward the base 69 of the fixation device 14, as indicated by arrow168. Due to the curvature of the proximal elements 16, such movement ofthe bridge 166 draws the proximal elements 16 inwardly toward the shaft12 (as indicated by arrows 170) which it turn draws the grasped leafletinwardly toward the shaft 12. Similarly, force applied to move thebridge 166 away from the base 69 moves the proximal elements 16outwardly. Thus, the leaflets may be repositioned by movement of thebridge 166. It may be appreciated that the bridge 166 may move towardthe base 69 due to movement of the distal elements 18 toward the closedposition. Or, the proximal elements 16 may be attached to a cam, orother suitable element, so as the distal elements 18 close, the proximalelements 14 are drawn inwardly toward the shaft 12. Thus, the proximalelements 16 may move while the distal elements 18 are static, or boththe proximal elements 16 and the distal elements 18 may move relative toeach other. It may further be appreciated that in some embodiments, thedistal elements 18 may move while the proximal elements 16 are static.

FIGS. 19A-19C illustrate an embodiment of a fixation device 14 similarto the fixation device 14 illustrated in FIG. 3 with the inclusion of apassageway through the shaft 12 for passage of a pre-grasper 176 asshown. The pre-grasper 176 has a shaft 178 and jaws 180 disposed nearits distal end 182, however any type of grasping mechanism may bepresent such as atraumatic hooks, clamps or claws. Referring to FIG.19B, the fixation device 14 is advanced through the mitral valve in anatrial approach as described above so that the fixation device 14resides within the ventricle. The pre-grasper 176 is advanced throughthe shaft 12 and manipulated to grasp a portion of one or both of theleaflets LF. The pre-grasper 176 may be steered by any suitablemechanisms, including pullwires, or the pre-grasper 176 may bepre-formed in a desired configuration. Further, the pre-grasper 176 maybe rotated within the shaft 12. The pre-grasper 176 may grasp oneleaflet or the pre-grasper 176 may grasp both leaflets, such as in acoapted orientation, to stabilize the leaflet(s) and/or move theleaflet(s) to a desired orientation. Once the leaflets aresatisfactorily oriented, the fixation device 14 may be used to grasp theleaflets LF as illustrated in FIG. 19C. The pre-grasper 176 may then bereleased from the leaflets LF and removed by withdrawal through thepassageway in the shaft 12. Alternatively, the pre-grasper 176 can beleft in place to reinforce the fixation of the leaflets.

In other embodiments the pre-grasper 176 is separately advanced to thetissue to leaflets LF, such as by a different approach. FIG. 20illustrates the fixation device 14 advanced via an atrial approach andthe pre-grasper 176 advanced via a ventricular approach. Again, thepre-grasper 176 has a shaft 178 and jaws 180 disposed near its distalend 182, however any type of grasping mechanism may be present such asatraumatic hooks, clamps or claws. The pre-grasper 176 is advanced andmanipulated to grasp a portion of one or both of the leaflets LF. Thepre-grasper 176 may be steered by any suitable mechanisms, includingpullwires, or the pre-grasper 176 may be pre-formed in a desiredconfiguration. Further, the pre-grasper 176 may be rotated. Thepre-grasper 176 may grasp one leaflet or the pre-grasper 176 may graspboth leaflets, such as in a coapted orientation, to stabilize theleaflet(s) and/or move the leaflet(s) to a desired orientation. Once theleaflets are satisfactorily oriented, the fixation device 14 may be usedto grasp the leaflet. LF the fixation device 14 is advanced through themitral valve in an atrial approach as described above so that thefixation device 14 resides within the ventricle. This is typicallyachieved by passing at least a portion of the fixation device 14 throughthe leaflets LF adjacent to the area of the leaflets grasped by thepre-grasper 176. The pre-grasper 176 may then be released from theleaflets LF and removed by withdrawal. Alternatively, the pre-grasper176 can be left in place to reinforce the fixation of the leaflets. Itmay be appreciated that in other embodiments, the fixation device 14 isadvanced via a ventricular approach and the pre-grasper 176 advanced viaan atrial approach.

FIGS. 21A-21B illustrate embodiments of a fixation device 14 having twosingle-sided fixation elements 190 joinable by a tether 192. Eachsingle-sided fixation element 190 is comprised of at least a proximalelement 16 and a distal element 18. In some embodiments, thesingle-sided fixation element 190 resembles one half of the fixationdevice 14 illustrated in FIG. 3. FIG. 21A illustrates a pair ofsingle-sided fixation elements 190, each fixation element 190 grasping aleaflet LF between its proximal element 16 and distal element 18. Thefixation elements 190 may be delivered to the leaflets LF through adelivery catheter 191, each element 190 connected to an elongatedelivery apparatus 193 which passes through the catheter 191. Thefixation elements 190 are also connected to each other by the tether192. Once, the fixation elements 190 have satisfactorily grasped theleaflets LF the fixation elements 190 may be detached from the deliveryapparatuses 193 and left behind to hold the leaflets LF in a desiredorientation via the tether 192. Alternatively, the tether 192 may beshortened or tensioned to draw the fixation elements 190 together,thereby coapting the leaflets LF. In some embodiments, such asillustrated in FIG. 21B, the tether 192 comprises a resilient element,such as a coil or spring, that “self-shortens” upon release from thecatheter 191. Other means of shortening or tensioning the tether 192 mayinclude applying a suture fastener to the tether 192, preferredembodiments of which are described and illustrated in U.S. patentapplication Ser. No. 10/087,004. In other embodiments, each one-sidedfixation element 190 is attached to an individual tether which extendsthrough the catheter 191. The individual tethers may then be knottedtogether, the knot being pushed toward the fixation elements 190 so asto tie them together at a desired distance.

Thus, the fixation elements 190 may be linked, attached, coupled orjoined together to hold the leaflets LF in the coapted position. It maybe appreciated that any number of single-sided fixation elements 190 maybe used, some or all of which may be joinable by one or more tethers192. Further, it may be appreciated that at least one of thesingle-sided fixation elements 190 may be used to grasp tissues otherthan valve leaflets, such as chordae, to assist in treatment of thevalve. For example, the elements 190 may join leaflet to leaflet,leaflet to papillary muscle, leaflet to chordae, etc. Still further, itmay be appreciated that each of the single-sided fixation elements 190may be deployed from opposite sides of the valve, such as from an atrialapproach and a ventricular approach, and joined across the valve. Thus,one single-sided fixation element 190 may be deployed on an anteriorside of the valve and one on a posterior side of the valve, the elements190 then cinched together to correct regurgitation.

FIG. 22 illustrates an embodiment of a fixation device 14 similar to thefixation device 14 illustrated in FIG. 3, including proximal elements 16and distal elements 18. However, in this embodiment, the distal elements18 are “self-engaging”. The fixation device 14 may be positioned withinthe mitral valve so that the distal elements 18 are disposed within theventricle and the proximal elements 16 are disposed within the atrium,as illustrated in FIG. 22. Rather than engaging the leaflets LF with thedistal elements 18 and then lowering the proximal elements 16 to graspthe leaflets LF therebetween, the proximal elements 16 are first loweredto engage the leaflets LF. Lowering of the proximal elements 16 maystabilize the leaflets LF and reduce possible upward motion or flailingof the leaflets LF. The distal elements 18 may then self-engage orautomatically move toward a closed position to engage the leaflets LFand grasp the leaflets LF between the proximal and distal elements 16,18. Self-engagement may be actuated by a variety of mechanisms,including a mechanism that signifies lowering of the proximal elements16 to a predetermined position or a sensor that senses sufficientengagement of the proximal elements 16 with the leaflets LF. It may beappreciated that the method of lowering the proximal elements 16 priorto engagement of the distal elements 18 may be utilized with thefixation device 14 of FIG. 3 without automatic engagement of the distalelements 18.

Once the leaflets have been grasped, a variety of features may assist inholding the grasped leaflets within the fixation device. For example,FIG. 23 illustrates an embodiment of a fixation device 14 having suctionto maintain leaflet position after grasping, particularly duringmovement of the distal elements 18 toward a closed position. In thisembodiment, suction lines 200 extend to suction ports 202 disposed onthe engagement surfaces 50 of the distal elements 18. The suction lines200 extend through the fixation device to a vacuum source similarly tothe embodiment illustrated in FIG. 15. Once the distal elements 18engage the leaflets with the engagement surfaces 50, suction appliedthrough the suction ports 202, assists to hold the leaflets against theengagement surfaces 50. Such suction may be applied prior to, duringand/or after lowering of any proximal elements 14 to hold the leafletstherebetween. As mentioned, such suction may be particularly helpful insecuring the leaflets within the fixation device 14 during movement ofthe distal elements 18 toward a closed position.

In another example, FIGS. 24A-24B illustrate an embodiment of a fixationdevice 14 having extended frictional accessories. As describedpreviously, the proximal elements 16 optionally include frictionalaccessories, frictional features or grip-enhancing elements to assist ingrasping and/or holding the leaflets. And, as described and illustratedin FIG. 5B, the frictional accessories may comprise barbs 60 havingtapering pointed tips extending toward engagement surfaces 50. FIG. 24Aillustrates proximal elements 16 having extended barbs 206 which aredirected toward engagement surfaces 50 of the distal elements 18.Likewise, FIG. 24B provides a closer view of the barbs 206 on theproximal elements 16 of FIG. 24A. As shown, the length L is extended.Such extended barbs 206 may be comprised of any suitable material,including rubber, flexible or rigid polymers or various metals. Inpreferred embodiments, the extended barbs 206 are atraumatic, theadditional length L providing increased surface area to hold theleaflets with frictional forces.

FIGS. 25A-25B illustrate an embodiment of a fixation device 14 having atextured gripping surface 212 to assist in holding the grasped leafletswithin the fixation device 14. An embodiment of the textured grippingsurface 212 is illustrated in FIG. 25A. The surface 212 includes aplurality of protrusions 214 which extend outwardly at an angle. Theprotrusions may be comprised of any suitable material, preferablyflexible material such as silicones, polymers, or fibers. Theprotrusions 214 are angled in a substantially uniform direction toprovide friction against an object moving in the opposite direction. Thetextured gripping surface 212 may be applied to any suitable portion ofthe fixation element 14, such as the proximal elements 14 or theengagement surfaces 50 of the distal elements 18. FIG. 25B illustrates afixation element 14 having the textured gripping surface 212 on acovering 210 over the distal elements 18. The covering 210 may bepresent to promote tissue growth. In this embodiment, the coveringcomprises a biocompatible fabric cover positioned over the distalelements 18. The covering 210 may optionally be impregnated or coatedwith various therapeutic agents, including tissue growth promoters,antibiotics, anti-clotting, blood thinning, and other agents.Alternatively or in addition, the covering 210 may be comprised of abioerodable, biodegradable or bioabsorbable material so that it maydegrade or be absorbed by the body after the repaired tissues have growntogether. It may be appreciated that such a covering 210 may cover thedistal elements 18 and/or proximal elements 16 of any of the fixationdevices 14 described herein. The textured gripping surface 212 is showndisposed on the covering 210 which covers the engagement surfaces 50.The protrusions 214 are angled toward the shaft 12. Therefore, leafletLF may be drawn toward the shaft 12 in the same direction as theprotrusions 214 encountering minimal friction. However, leaflet LF′moving away from the shaft 12 encounters significant friction from theprotrusions 214 as the protrusions 214 are engaged and resist movementof the leaflet LF′. Thus, the textured gripping surface 212 resistsmovement of the leaflets away from the shaft 12, assisting in holdingthe grasped leaflets within the fixation device 14.

FIGS. 26A-26B illustrate another embodiment of a fixation device 14having a textured gripping surface 212 to assist in holding the graspedleaflets within the fixation device 14. In this embodiment, the surface212 includes a plurality of protrusions 214 which extend outwardly at anangle. The protrusions may be comprised of any suitable material,preferably a rigid material capable of piercing into and/or through theleaflet. Therefore, the protrusions may also be pointed or sharpened.The textured gripping surface 212 may be applied to any suitable portionof the fixation element 14, preferably the engagement surfaces 50 of thedistal elements 18. FIG. 26A shows leaflets LF grasped by the distalelements 18, the protrusions 214 extending through the leaflets LF whichassist in holding the leaflets LF in place. The proximal elements 16 maythen be released, grasping the leaflets LF between the proximal anddistal elements 16, 18. In some embodiments, the proximal elements 16apply force to the protrusions 214, bending the protrusions 214 towardthe engagement surfaces 50 so that the protrusions 214 “staple” theleaflets LF to the engagement surfaces 50, as illustrated in FIG. 26B.Alternatively, the protrusions 214 may have barbed or arrowhead shapedtips which may similarly act to staple the leaflets LF to the engagementsurfaces 50.

IV. Grasping Assessment

Once the tissue or leaflets have been grasped, it is often desired toevaluate or assess the quality of the grasp, such as the amount ofpurchase, orientation of the tissues, and likelihood that the fixationdevice will maintain the grasp over time. Thus, a variety of devices andtechniques are provided to assess the grasp. It may be appreciated thatthe assessment devices and techniques may be used in combination withthe above described fixation devices or may be used with any suitablegrasping and/or fixing device. Further, many of such assessment devicesand techniques may be used to assess grasping of valve leaflets, orother tissues, for any purpose.

One method of determining quality of grasp is to visualize the grasp bymeans of fluoroscopy, ultrasound, echocardiography or other knownvisualization techniques. Using these techniques, a physician orpractitioner may be able to observe an image of the fixation device andthe grasped tissue to determine if the grasp is desirable. The fixationdevice may be visually differentiated from the surrounding tissue byenhancing the visibility of portions of the surrounding tissue,particularly the tissue intended to be grasped, such as the valveleaflets. Thus, as illustrated in FIGS. 27A-27B, the leaflets LF may beinjected with a substance which enhances visibility prior to and/orafter grasping with the fixation device. Example substances includeliquid contrast material or bioabsorbable polymer beads having airbubbles trapped within. As shown in FIG. 27A, an injection catheter 220having a needle 222 may be advanced to the leaflet LF to inject thesubstance. Exemplary injection catheters are described in U.S. Pat. Nos.6,685,648; 4,578,061; 6,540,725; 6,165,164. FIG. 27B illustrates aleaflet LF having the substance 224 injected therein (as indicated byshading) and another leaflet being injected by the needle 222 of theinjection catheter 220.

Alternatively, portions of the fixation device may have enhancedvisibility to differentiate the fixation device from the surroundingtissue. For example, FIG. 28 illustrates a fixation device 14 whereinthe proximal elements 16 and distal elements 18 have enhancedvisibility, as indicated by shading. Such enhanced visibility may assistdifferentiation of the proximal and distal elements 16, 18 from valveleaflets LF captured therebetween. Further, the practitioner may be ableto determine where the leaflet edges E are located with respect to theproximal and distal elements 16, 18, e.g. how closely the edges E are tothe shaft 12. This may indicate the size of the purchase. In someembodiments, surfaces of the fixation device are roughened, such as bybead blasting, to enhance visibility such as echogenicity. In otherembodiments, at least portions of the fixation device 14 have anenhanced visibility covering. Such a covering may be comprised of clothhaving titanium threads, spun polyester or other material which providesechogenicity. Alternatively or in addition, the covering may be stampedor impregnated with materials which provide echogenicity, such as bariumsulfate. Or, the visibility of the covering may be enhanced by a bulkyappearance of the covering.

In some embodiments, the fixation device includes an ultrasoundreceiving indicator. The ultrasound receiving indicator is typicallydisposed along a proximal or distal element near a target area. Theindicator is used to determine the presence or absence of tissue withinthe target area thereby assessing the quality of the grasp. Theindicator comprises a chip or other device that resonates or vibrates ata specific ultrasonic frequency which differs from the general frequencyused to visualize the remainder of the fixation device and thesurrounding tissue. Therefore, when the specific ultrasonic frequency isused for visualization, the indicator provides a bright visual artifacton an echocardiogram image. This indicates that the tissue is notsufficiently grasped within the target area because the indicator isfreely vibrating. However, if the tissue is compressed between theproximal and distal elements within the target area, the tissuecompresses the indicator, reducing or damping the vibration of theindicator. Thus, if the bright visual artifact is not seen at thespecific ultrasonic frequency, it may be determined that the tissue issufficiently grasped within the target area of the fixation device. Thisallows the practitioner to actively evaluate the grasp by viewing adynamic change in the image being viewed at the time of interrogationwith the specific ultrasonic frequency.

Alternatively, the indicator may comprise a chip or other device thatresonates at the same general frequency used to visualize the remainderof the fixation device and the surrounding tissue. When the generalfrequency is used for visualization, the indicator provides a brightvisual artifact on an echocardiogram image. This indicates that thetissue is not sufficiently grasped within the target area because theindicator is freely vibrating. Again, if the tissue is compressedbetween the proximal and distal elements within the target area, thetissue compresses the indicator, reducing or damping the vibration ofthe indicator. Thus, if the bright visual artifact is not seen at thegeneral ultrasonic frequency, it may be determined that the tissue issufficiently grasped within the target area of the fixation device. Thisallows the practitioner to evaluate the grasp by viewing more staticimages of the echocardiogram. It may be appreciated that the abovedescribed ultrasound receiving indicators may both be used with realtime ultrasonic images, however one allows evaluation of the grasp basedon viewing a dynamic change in an image due to interrogation with aspecific ultrasonic frequency and the other allows evaluation of thegrasp based on viewing a more static image at a general ultrasonicfrequency.

In other embodiments, the fixation device includes a magnetic indicator.The magnetic indicator is typically disposed along a proximal or distalelement near a target area. The indicator is used to determine thepresence or absence of tissue within the target area thereby assessingthe quality of the grasp. The indicator comprises a device, such as aball bearing, that is movable when a magnetic field is applied. Such amagnetic field may be locally applied, such as by a catheter, orglobally applied, such as by magnetic resonance imaging. Movement of theindicator may be visualized by any suitable medium, such as fluoroscopy.Such movement indicates that the tissue is not sufficiently graspedwithin the target area because the indicator is freely movable. However,if the tissue is compressed between the proximal and distal elementswithin the target area, the tissue compresses the indicator, reducing ordamping the movement of the indicator. Thus, if movement is reduced ornot seen when the magnetic field is applied, it may be determined thatthe tissue is sufficiently grasped within the target area of thefixation device. This allows the practitioner to actively evaluate thegrasp.

In other embodiments, the position of a grasped leaflet within afixation device may be determined based on the visibility of frictionalelements. Such frictional elements typically have an observable shape,such as barbs, and are coated or comprised of an enhanced visibilitymaterial. FIG. 29 illustrates a fixation device 14 having such barbs 60disposed on the proximal elements 16 as frictional elements. In thisembodiment, the proximal elements 16 have a visually opaque orsemi-opaque covering 230 which cover the barbs 60. The covering 230 maybe comprised of, for example, fibers made from gold or platinum wire orpolymer fibers coated or sputtered for radiopacity. When a leaflet LF isgrasped and captured between the proximal element 16 and distal element18, the leaflet LF presses the covering 230 against the proximal element16 causing the barbs 60 to extend through the covering 230. The exposedbarbs 60 are visibly observable by visualization techniques. Thequantity and location of visible barbs 60 indicates the position of thegrasped leaflet. For example, when a leaflet LF′ is grasped andpartially captured between the proximal element 16′ and distal element18′, only a portion of the barbs 60 (such as single barb 60′) areexposed. Thus, the low quantity and outward location of the visible barb60′ indicate that the leaflet LF is not fully captured. The leaflet LFmay then be released and regrasped.

In still other embodiments, the position of a grasped leaflet within afixation device may be determined based the visible shape of theproximal elements 16. In such embodiments, the proximal elements 16 maybe comprised of segmental parts separated by hinges or flexible areas240, as illustrated in FIG. 30. The proximal elements 16 are coated orcomprised of an enhanced visibility material. When a leaflet LF isgrasped and fully captured between the proximal element 16 and distalelement 18, the proximal element 16 has a shape which substantiallyfollows the contour of the distal element 18. When a leaflet LF′ isgrasped and partially captured between the proximal element 16′ anddistal element 18′, the proximal element 16′ may flex at a flexible area240 near an edge E′ of the partially captured leaflet LF′. The proximalelement 16′ may also flex due to a variety of other misorientations ofthe grasped leaflet LF′. Visualization of the shape of the segmentalproximal element indicates the locations in which irregularities occurwhich may indicate how much of the leaflet has been captured. If theleaflet is not desirably captured, the leaflet LF may then be releasedand regrasped.

In additional embodiments, the position of a grasped leaflet within afixation device may be determined based the visibility of an indicatorassociated with the distal elements 18. For example, FIGS. 31A-31Billustrate an embodiment of a fixation device 14 having a distal element18 which includes a flap 240. The flap 240 has an attached end 242 whichis attached to the engagement surface 50 or a portion of the distalelement 18 and a free end 244 which extends toward the proximal element16. The flap 240 forms an angle θ with the engagement surface 50. Theflap 240 is typically flexible or is attached so that the flap 240 isable to move throughout the angle θ. The flap 240 is coated or comprisedof an enhanced visibility material so that the practitioner may observethe flap 240 and its angle θ by visualization techniques. In preferredembodiments, the distal element 18 is also coated or comprised of anenhanced visibility material. Prior to grasping a tissue, such as aleaflet, the flap 240 is fully visible and is positioned having amaximum angle θ, as illustrated in FIG. 31A. When a leaflet LF isgrasped between the proximal and distal elements 16, 18, the leaflet LFpresses the flap 240 toward the engagement surface 50. When the leafletLF is fully captured, the leaflet LF may press the flap 240 so that itis parallel with or uniform with the engagement surface 50, asillustrated in FIG. 31B. Thus, the lack of observable flap 240 may be anindicator that the leaflet LF has been satisfactorily grasped.Alternatively, the practitioner may be able to determine the extent ofgrasp or purchase based on the angle θ. For example, flap 240 having anangle (θ/2) may indicate that the leaflet LF only extends half way alongthe engagement surface 50. If this is not desirable, the leaflet LF maythen be released and regrasped. It may be appreciated that the flap 240may have any suitable shape, size or location, including location on aproximal element 16 or any other suitable element. Further, more thanone flap 240 may be present.

FIGS. 32A-32C illustrate another embodiment wherein the position of agrasped leaflet within a fixation device may be determined based thevisibility of an indicator associated with the distal elements 18. Herethe indicator comprises a floating block 248 associated with the distalelement 18. The floating block 248 is coupled with the distal element 18so that it may pass through the distal element 18 upon application offorce. The block 248 is coated or comprised of an enhanced visibilitymaterial so that the practitioner may observe the block 248 byvisualization techniques. In preferred embodiments, the distal element18 is also coated or comprised of an enhanced visibility material.Typically, the block 248 biased, such as spring biased, so that theblock 248 is raised toward the proximal element 14, as illustrated inFIG. 32A, prior to grasping a tissue, such as a leaflet. When a leafletLF is grasped between the proximal and distal elements 16, 18, theleaflet LF presses the block 248 toward the engagement surface 50. Whenthe leaflet LF is partially captured, as illustrated in FIG. 32B, aportion of the block 248 may be visible raised from the engagementsurface 50 and a portion may be visible extending from the oppositeside. The practitioner may determine the position of the leaflet LFbased on the rotation point of the block 248. When the leaflet LF isfully captured, as illustrated in FIG. 32C, the leaflet LF may move theblock 248 so that it is fully passed through the distal element 18 andextends outwardly from the opposite side. Thus, the practitioner maydetermined the desirability of the grasp based on the position of thefloating block 248. It may be appreciated that the block 248 may haveany suitable shape, size or location including location on a proximalelement 16 or any other suitable element. Further, more than one block248 may be present.

FIG. 33 illustrate an embodiment wherein the indicator comprises abladder or reservoir 249 associated with the distal element 18. Thereservoir 249 is coupled with the distal element 18 so that it may passthrough the distal element 18 upon application of force. The reservoir249 is filled with an enhanced visibility material so that thepractitioner may observe the reservoir 249 by visualization techniques.Typically, the reservoir 249 is positioned so that it is raised towardthe proximal element 14, as illustrated in the left side of FIG. 33,prior to grasping a tissue, such as a leaflet LF. When a leaflet LF isgrasped between the proximal and distal elements 16, 18, as illustratedin the right side of FIG. 33, the leaflet LF presses the reservoir 249toward the engagement surface 50. When the leaflet LF is partiallycaptured, a portion of the reservoir 249 may be visible raised from theengagement surface 50 and a portion may be visible extending from theopposite side. The practitioner may determine the position of theleaflet LF based on the position of the reservoir 249. When the leafletLF is fully captured, the leaflet LF may move the reservoir 249 so thatit is fully passed through the distal element 18 and extends outwardlyfrom the opposite side. Thus, the practitioner may determined thedesirability of the grasp based on the position of the reservoir 249.

Similarly, as illustrated in FIGS. 34A-34B, the reservoir 249 may haveparticular size, shape, and/or location so that when both reservoirs 249are appropriately displaced (indicating both leaflets satisfactorilygrasped) the reservoirs 249 may come together to form a distinctive sizeor volume, as illustrated in FIG. 34B. This may indicate to thepractitioner that the leaflets LF are desirably grasped. It may beappreciated that the reservoirs 249 of FIG. 33 and FIGS. 34A-34B mayhave any suitable shape, size or location including location on aproximal element 16 or any other suitable element. Further, more thanone reservoir 249 may be present.

FIG. 35 illustrates another embodiment wherein the position of a graspedleaflet within a fixation device may be determined based the visibilityof an indicator associated with the distal elements 18. Here theindicator comprises one or more loops 251, such as wire loops,associated with the distal element 18. The loops 251 are coupled withthe distal element 18 so that the loops 251 may pass through the distalelement 18 upon application of force. The loops 251 are coated orcomprised of an enhanced visibility material so that the practitionermay observe the loops 251 by visualization techniques. Typically, theloops 251 are biased, such as spring biased, so that the loops 251 areraised toward the proximal element 14, as illustrated in the left sideof FIG. 35, prior to grasping a tissue, such as a leaflet LF. When aleaflet LF is grasped between the proximal and distal elements 16, 18,the leaflet LF presses the loops 251 toward the engagement surface 50.When the leaflet LF is fully captured, as illustrated in the right sideof FIG. 35, the leaflet LF may move the loops 251 so that they are fullypassed through the distal element 18 and extend outwardly from theopposite side. Thus, the practitioner may determine the desirability ofthe grasp based on the position of the loops 251. It may be appreciatedthat the loops 251 may have any suitable shape, size or locationincluding location on a proximal element 16 or any other suitableelement.

FIGS. 36A-36B illustrate another embodiment wherein the position of agrasped leaflet within a fixation device may be determined based thevisibility of an indicator associated with the distal elements 18. Herethe indicator comprises at least one slackline 265, such a wire, suture,thread, filament, polymer, or strand, which extends around portions ofthe fixation device 14. In this embodiment, as shown in FIG. 36A, theslackline 265 extends through a lumen in catheter 86 and along the shaft12 toward the base 69 of the fixation device 14. The slackline 265 thenextends around a free end 54′ of one of the distal elements 18′ andcontinues across to a free end 54″ of the opposite distal element 18″,creating an indicator segment 265 a between the distal elements 18′,18″. The slackline 265 then extends toward the base 69 and returns alongthe shaft 12 to another lumen (or the same lumen) in catheter 86. Theslackline 265 is coated or comprised of an enhanced visibility materialso that the practitioner may observe the slackline 265 by visualizationtechniques. The slackline 265 also has sufficient slack to allowmovement of at least the indicator segment 265 a when force is applied,such as by a leaflet. FIG. 36B illustrates the fixation device 14 ofFIG. 36A wherein a pair of leaflets LF are desirably grasped. Here,desirable positioning of the leaflets between the proximal elements 16′,16″ and distal elements 18′, 18″ forces the indicator segment 265 a intoa different configuration, in this case lowering the indicator segment265 a. Thus, the practitioner may determine the desirability of thegrasp based on the position of the indicator segment 265 a. It may beappreciated that the indicator segment 265 a and/or the slackline 265may have any configuration, and more than one slackline 265 may bepresent.

In other embodiments, the position of one or more leaflets LF within thefixation device 14 may be determined or verified prior to releasing ofthe proximal elements 16. For example, FIG. 37A illustrates anembodiment of a fixation device 14 having mini-grippers 263 which may beshaped similarly to the proximal elements 16 yet are smaller in size.Each mini-gripper 263 is disposed between a set of proximal and distalelements 16, 18. The fixation device 14 is positioned to so that theleaflets are engaged by the engagements surfaces 50 of the distalelements 18. The mini-grippers 263 are then released, each extendingradially outwardly from the shaft 12 a short distance along theengagement surfaces 50 of the distal elements 18. It may be appreciatedthat the mini-grippers 263 may be released independently orsimultaneously. If the mini-grippers 263 grasp the leaflets, it may bedetermined that the leaflets are adequately positioned within thefixation device 14 since such grasping indicates that the leafletsextend to a desired distance relative to the shaft 12. Once desiredgrasping of the leaflets is determined, the proximal elements 16, may bereleased to grasp the leaflets between the proximal and distal elements16, 18. The mini-grippers 263 may remain in place or be removed.

Alternatively, both the mini-grippers 263 and the proximal elements 16may be deployed simultaneously. The proximal elements 16 may then beraised or released while the mini-grippers 263 remain deployed, therebyconfirming whether the leaflets are still held by the mini grippers 263.If the mini-grippers 263 still hold the leaflets, it may be determinedthat the leaflets are adequately positioned within the fixation device14 since such grasping indicates that the leaflets extend to a desireddistance relative to the shaft 12. Once desired grasping of the leafletsis determined, the proximal elements 16, may be re-released to grasp theleaflets between the proximal and distal elements 16, 18. Themini-grippers 263 may remain in place or be removed.

In yet other embodiments, as illustrated in FIG. 37B, the mini-grippers263 may extend through a window 265 or space in the distal elements 18if the released mini-grippers 263 do not contact the leaflets in thetarget area. Thus, visualization of the mini-grippers 263 extendingbeyond the distal elements 18, as shown, indicates that the leafletshave not been desirably grasped. Such visualization may be achievedprior to or after release of the proximal elements 16. When themini-grippers 263 are released simultaneously with the proximal elements16, such visualization allows grasping assessment to be achieved withoutadditional movement of the proximal elements 16.

In other embodiments, the position of a grasped leaflet within afixation device may be determined based the visibility of a releasedsubstance which is visible under visualization techniques, such asliquid contrast material or bioabsorbable polymer beads having airbubbles trapped within. In one embodiment illustrated in FIG. 38A, thesubstance 258 is contained in a bladder or reservoir 260 within thedistal element 18. When a leaflet LF is grasped between the proximal anddistal elements 16, 18, the leaflet LF presses the reservoir 260releasing the substance 258 through ports 262, as illustrated in FIG.38B. The ports 262 may be disposed along the length of the distalelement 18 so that the substance 258 is expelled through the ports 262only in the areas where the leaflet LF is engaged. Therefore, thepractitioner may be able to determine the extent of grasp or purchasebased on the location and/or amount of expelled substance 258. It may beappreciated that the reservoir 260 may have any suitable shape, size orlocation, including location on a proximal element 16 or any othersuitable element. Further, more than one reservoir 260 may be present.

Another embodiment, illustrated in FIGS. 39A-39B, the position of agrasped leaflet LF within a fixation device 14 is also determined basedthe visibility of a released substance which is visible undervisualization techniques, such as liquid contrast material orbioabsorbable polymer beads having air bubbles trapped within. Here, thesubstance 258 is released through a lumen 270 which extends through theshaft 12 and through a conduit 272, as illustrated in FIG. 39A. Theconduit 272 is directed toward a target area of the engagement surface50 of the distal element 18. The target area is positioned so that agrasped leaflet LF covering the target area is considered sufficientlygrasped. When a leaflet LF covers the target area, as illustrated inFIG. 39A, the released or injected substance 258 is blocked by theleaflet LF. Such blockage may either prevent injection of the substance258, cause injection of the substance 258 into the leaflet LF, or allowsome visibility of the substance 258 on the side of the leaflet LFreceiving the injected substance 258. Thus, the practitioner maydetermine that the leaflet LF is satisfactorily grasped due to the lackof or reduced quantity of substance 258 or the location of the injectedsubstance 258 (i.e. within the leaflet or on the side of the leafletreceiving the injected substance 258). When a leaflet LF does not coverthe target area, as illustrated in FIG. 39B, the released or injectedsubstance 258 is not blocked by the leaflet LF. Therefore, the substance258 will be injected into the area between the proximal and distalelements 16, 18 and is free to extravagate into the circulation. Thus,the practitioner may determine that the leaflet LF is not satisfactorilygrasped due to the visibility of extravagated substance 258. It may beappreciated that the conduit 272 may have a variety of forms, sizes andorientations and may be directed toward a variety of target areas.Further, more than one conduit 272 may be present. It may also beappreciated that needles, tubes or other instruments may be advancedthrough the conduit 272 to deliver the substrate or for any otherpurpose.

It may also be appreciated that the above described lumen 270 andconduit 272 may alternatively be used to draw suction. When a leaflet LFcovers the target area, as illustrated in FIG. 39A, suction drawnthrough the conduit 272 will cause the leaflet LF to press against theconduit 272 preventing blood from entering the conduit 272. However,when a leaflet LF does not cover the target area, blood will besuctioned up through the conduit 272. Therefore, the practitioner maydetermine whether the leaflet LF is satisfactorily grasped based on thepresence of blood suctioned through the conduit 272.

Similarly, an embodiment, illustrated in FIGS. 40A-40B, is providedhaving a lumen 270 which extends through the shaft 12 and through aconduit 272. Again, the conduit 272 is directed toward a target area ofthe engagement surface 50 of the distal element 18. The target area ispositioned so that a grasped leaflet LF covering the target area isconsidered sufficiently grasped. In this embodiment, a probe 280 isadvanceable through the lumen 270. In addition, the probe 280 isconnected with an insertion depth gauge 282 so that the practitioner isable to determine the advancement distance of the probe 280. When aleaflet LF covers the target area, as illustrated in FIG. 40A, the probe280 may only be advanced until it contacts the leaflet LF. Thus, thepractitioner may determine that the leaflet LF is satisfactorily graspeddue to the minimal advancement distance indicated by the insertion depthgauge 282. When a leaflet LF does not cover the target area, asillustrated in FIG. 40B, the probe 280 is able to advance further towardthe distal element 18. Thus, the practitioner may determine that theleaflet LF is not satisfactorily grasped due to the advancementdistance. Again, it may be appreciated that the conduit 272 may have avariety of forms, sizes and orientations and may be directed toward avariety of target areas. Further, more than one conduit 272 may bepresent.

Similarly, as illustrated in FIGS. 41A-41F, detectable elements 281 mayextend from the shaft 12. In FIGS. 41A-41B, the detectable elements 281are coupled with the proximal elements 16 so that release of eachproximal element 16 draws an associated detectable element 281 toward atarget area of the engagement surface 50 of the associated distalelement 18. Each target area is positioned so that a grasped leaflet LFcovering the target area is considered sufficiently grasped. When aleaflet LF′ covers its corresponding target area, as illustrated in theleft side of FIG. 41A, the detectable element 281′ contacts the leafletLF′. When a leaflet LF″ does not cover its corresponding target area, asillustrated in the right side of FIG. 41A, the detectable element 281″is able to advance toward the target area, extending a further distancethan if a leaflet were present. The detectable elements 281′, 281″ arecomprised of a detectable material or coating, such as a material whichis detectable by fluoroscopy, conductance or impedance signal.Therefore, the practitioner is able to detect the position of thedetectable elements 281′, 281″ and consequently determine if theleaflets are desirably grasped, as illustrated in FIG. 41B. Thedetectable elements 281′, 281″ are then released from the proximalelements 16 and removed upon detachment of the fixation device 14. Itmay be appreciated that the detectable elements 281 may be individuallyextendable from the shaft 12 (i.e. not coupled with the proximalelements 16). Also, in other embodiments, the detectable elements 281may form a circuit when contacting the engagement surface 50 of theassociated distal element 18. For example, when a leaflet LF′ covers itscorresponding target area, the detectable element 281′ contacts theleaflet LF′, such as illustrated above in the left side of FIG. 41A.Thus, the detectable element 281′ does not contact the engagementsurface 50 and the circuit remains open. When a leaflet LF″ does notcover its corresponding target area, such as illustrated in the rightside of FIG. 41A, the detectable element 281″ is able to advance towardthe target area and contact the engagement surface, completing thecircuit. The integrity of the circuit may be detected by any suitabledevice, such as an ohmmeter or an ammeter, thereby indicating if theleaflets are desirably grasped.

In FIGS. 41C-41D, the detectable elements 281 are each advanceable fromthe shaft 12 toward a target area of the engagement surface 50 of itsassociated distal element 18. When a leaflet LF′ covers itscorresponding target area, as illustrated in the left side of FIG. 41C,the detectable element 281′ contacts the leaflet LF′ and creates a firstshape. When a leaflet LF″ does not cover its corresponding target area,as illustrated in the right side of FIG. 41C, the detectable element281″ is able to advance toward the target area, creating a second shapewhich differs from the first shape. The detectable elements 281′, 281″are comprised of a detectable material or coating, such as a materialwhich is detectable by fluoroscopy or by impedance signal. Therefore,the practitioner is able to detect the shapes of the detectable elements281. When both leaflets are desirably grasped, both detectable elements281′, 281″ will substantially form the first shape, as illustrated inFIG. 41D.

In FIGS. 41E-41F, a single detectable element 281 is advanceable fromthe shaft 12 toward target areas of the engagement surfaces 50 of thedistal elements 18. When a leaflet LF′ covers its corresponding targetarea, as illustrated in the left side of FIG. 41E, a portion 283′ of thedetectable element 281 contacts the leaflet LF′ and creates a firstshape. When a leaflet LF″ does not cover its corresponding target area,as illustrated in the right side of FIG. 41F, a portion 283″ of thedetectable element 281 is able to advance toward the target area,creating a second shape which differs from the first shape. Thedetectable element 281 is comprised of a detectable material or coating,such as a material which is detectable by fluoroscopy or by impedancesignal. Therefore, the practitioner is able to detect the shape of theportions 283′ 283″ of the detectable element 281. When both leaflets aredesirably grasped, both portions 283′ 283″ of the detectable element 281will substantially form the first shape, as illustrated in FIG. 41F,creating a symmetrical shape.

In some embodiments, the fixation device includes one or more sensors todetermine the position of a grasped tissue. Typically, the sensordetermines the presence or absence of tissue on or near the sensor. Forexample, FIGS. 42A-42B illustrate a fixation device 14 having at leastone sensor 290 disposed on or within a distal element 18. In thisembodiment, the sensor 290 is positioned near the shaft 12 to determineif a grasped leaflet LF is fully inserted into the fixation device 14 oronly partially inserted. As shown in FIG. 42A, the sensor 290 may emit afirst signal 292 when the leaflet LF is not detected near the sensor 290indicating that the leaflet LF is not fully engaged. When the leaflet LFis fully engaged, as illustrated in FIG. 42B, the sensor 290 detects theleaflet LF near the sensor 290 and emits a second signal 294, whichdiffers from the first signal 292. The sensor 290 may have any suitableform, such as a conductor, a strain gauge, a radiosensor, an opticalsensor, an ultrasound sensor, an infrared sensor, an electricalresistance sensor, an intravascular ultrasound (IVUS) sensor or apressure sensor, to name a few. Alternatively, the sensor 290 maycomprise a resonating sensor that responds to magnetic energy in thefixation device 14 to indicate leaflet insertion. For example, magneticenergy may be applied to the fixation device 14 wherein the sensor 290does not resonate or is not activated if the leaflet is not sufficientlyinserted. It may be appreciated that any number of sensors 290 may bepresent and may be disposed on or within any element, including theproximal elements 16. FIG. 43 illustrates a fixation device 14 havingsensors 290 which extend into a target area between the proximal anddistal elements 16, 18.

FIGS. 44A-44B illustrate a fixation device 14 having sensors 290′, 290″positioned on the shaft 12. In this embodiment, the sensors 290′, 290″emit ultrasound signals toward a portion of the distal elements 18 nearthe shaft 12. In FIG. 44A, leaflet LF″ is not detected by the sensor290″ since the leaflet LF″ is not grasped between the correspondingproximal and distal elements 16, 18 and the leaflet LF″ does not extendinto the path of the emitted signals. The practitioner may thenreposition the fixation device 14. FIG. 44B illustrates a fixationdevice 14 having both leaflets LF′, LF″ desirably grasped so that bothsensors 290′, 290″ sense the leaflets LF′, LF″.

It may also be appreciated that sensors may be used to actuate movementof the fixation device. For example, sensors in the form of straingauges may be disposed on each of the distal elements. Engaging thedistal elements with the leaflets applied tension to the distal elementswhich is measurable by the strain gauges. Therefore, when the straingauges measure a predetermined quantity, the proximal elements may beautomatically lowered to grasp the leaflets therebetween. It may beappreciated that the strain gauge measurements may be used to actuate avariety of other movements or simply indicate to the practitioner thatsuch movements are acceptable.

V. Fixation Assessment

Once the quality of the grasp of the tissue has been assessed, it isoften desired to evaluate or assess the quality of the fixation of thetissue. This can be achieved by evaluating the improvement in themedical condition being treated. In the case of valve leaflet fixation,improvement in regurgitation may be evaluated. It is often desired toassess the fixation prior to decoupling the fixation device from thedelivery catheter so that the fixation device may be repositioned if theimprovement is not satisfactory. Thus, a variety of devices andtechniques are provided to assess the fixation prior to decoupling thefixation device from the delivery catheter. It may be appreciated thatthe assessment devices and techniques may be used in combination withthe above described fixation devices or may be used with any suitablegrasping and/or fixing device. Further, many of such assessment devicesand techniques may be used to assess fixation for any purpose.

FIGS. 45A-45B illustrate an embodiment of devices and methods forsimulating the resultant placement and function of a fixation device 14that has been positioned to grasp leaflets LF of the mitral valve MV. Inthis embodiment, the fixation device 14 is delivered to the mitral valveMV by a catheter 86. The fixation device 14 is removably coupled to ashaft 12 which is passed through a catheter 86. In addition, a sheath300 is provided which passes through the catheter 86 and over the shaft12 to provide support while the fixation device 14 is positioned withinthe valve MV and the leaflets LF are grasped between the proximal anddistal elements 16, 18. Once the leaflets LF are satisfactorily grasped,the sheath 300 may be retracted, as illustrated in FIG. 45B. Retractionof the sheath 300 exposes a flexible linkage 302 which extends from theshaft 12 to the catheter 86. The flexible linkage 302 allows thefixation device 14 to move freely, mimicking the behavior of thefixation device 14 after decoupling from the shaft 12. The improvementin regurgitation may then be assessed. If the improvement is consideredunsatisfactory, the sheath 300 may be advanced to cover the flexiblelinkage 302 and provide support for repositioning of the fixation device14. Upon repositioning, the sheath 300 may then be retracted and thefunction of the valve again assessed. This may be repeated as many timesas desired. Once the improvement is considered satisfactory, thefixation device 14 may be decoupled from the shaft 12.

Similarly, FIGS. 46A-46B also illustrate an embodiment of devices andmethods for simulating the resultant placement and function of afixation device 14 that has been positioned to grasp leaflets LF of themitral valve MV. In this embodiment, the fixation device 14 is deliveredto the mitral valve MV by a catheter 86. The fixation device 14 isremovably coupled to a shaft 12 which is passed through a catheter 86.Here, the shaft 12 is comprised of a flexible structure 306, such as acompression coil, that is held rigid by a center actuation wire 308. Thewire 308 is held taught to provide support while the fixation device 14is positioned within the valve MV and the leaflets LF are graspedbetween the proximal and distal elements 16, 18. Once the leaflets LFare satisfactorily grasped, the wire 308 tension is released to allowthe flexible structure 306 to flex which allows the fixation device 14to move freely, mimicking the behavior of the fixation device 14 afterdecoupling from the shaft 12. The improvement in regurgitation may thenbe assessed. If the improvement is considered unsatisfactory, thetension may be reapplied to the wire 308 to provide support forrepositioning of the fixation device 14. Upon repositioning, tension mayagain be released and the function of the valve assessed. This may berepeated as many times as desired. Once the improvement is consideredsatisfactory, the fixation device 14 may be decoupled from the shaft 12.

In other embodiments, the fixation device may be decoupled from theshaft while maintaining a tether, such as a suture line, to thecatheter. This allows the fixation device 14 to be evaluated while it isdecoupled from the shaft but provides assistance in retrieval of thefixation device for repositioning. The tether may be presentspecifically for this purpose, or other elements used in the positioningof the fixation device 14 may be used as a tether, such as a lock line92 or a proximal element line 90. Alternatively, a snare may be extendedfrom the catheter 86 to retrieve the fixation device 14. In any case,the fixation device may be retrieved with the tether, recounted with theshaft 12 and repositioned until a satisfactory result is achieved.

Although the foregoing invention has been described in some detail byway of illustration and example, for purposes of clarity ofunderstanding, it will be obvious that various alternatives,modifications and equivalents may be used and the above descriptionshould not be taken as limiting in scope of the invention which isdefined by the appended claims.

What is claimed is:
 1. A system for fixation of leaflets of a heartvalve comprising: an implantable fixation device comprising: a first armand a second arm, a first gripping element moveable relative to thefirst arm between a first first-gripping-element position and a secondfirst-gripping-element position, wherein the first arm and the firstgripping element are disposed on a first side of the implantablefixation device to define a first target area, and a second grippingelement moveable relative to the second arm between a firstsecond-gripping-element position and a second second-gripping-elementposition, wherein the second arm and the second gripping element aredisposed on a second side of the implantable fixation device to define asecond target area; a delivery device comprising: a catheter having ashaft having a proximal end portion and a distal end portion, theimplantable fixation device releasably mounted at the distal endportion, the catheter defining a lumen extending between the proximalend portion and the distal end portion and through a conduit extendinglaterally from the shaft and configured for release of a substancevisible under visualization techniques directed toward at least one ofthe first target area or the second target area; and a visualizationsubstance releasable through the lumen and visible under visualizationtechniques.
 2. The system of claim 1, wherein the conduit is directedtoward the first target area.
 3. The system of claim 1, wherein thevisualization substance comprises liquid contrast material.
 4. Thesystem of claim 1, wherein the visualization substance comprisesbioabsorbable polymer beads.
 5. The system of claim 1, wherein theconduit is directed toward the second target area.
 6. A methodcomprising: advancing a system for fixation of leaflets of a heart valvecomprising: an implantable fixation device comprising a first arm and asecond arm, a first gripping element moveable relative to the first armbetween a first first-gripping-element position and a secondfirst-gripping-element position, wherein the first arm and the firstgripping element are disposed on a first side of the implantablefixation device to define a first target area, and a second grippingelement moveable relative to the second arm between a firstsecond-gripping-element position and a second second-gripping-elementposition, wherein the second arm and the second gripping element aredisposed on a second side of the implantable fixation device to define asecond target area; and a delivery device comprising a catheter having ashaft and having a proximal end portion and a distal end portion, theimplantable fixation device releasably mounted at the distal endportion, the catheter defining a lumen extending between the proximalend portion and the distal end portion and through a conduit extendinglaterally from the shaft and configured for release of a substancevisible under visualization techniques directed toward at least one ofthe first target area or the second target area; releasing avisualization substance through the lumen; observing the visualizationsubstance released through the lumen using a visualization technique;and determining a position of one or more of a leaflet, the firstgripping element, and the first arm from the observed visualizationsubstance.
 7. The method of claim 6, wherein the visualization substancecomprises liquid contrast material.
 8. The method of claim 6, whereinthe visualization substance comprises bioabsorbable polymer beads. 9.The method of claim 6, further comprising directing the visualizationsubstance toward a target area.
 10. The method of claim 9, wherein thetarget area comprises the first gripping element.
 11. The method ofclaim 6, wherein determining a position comprises determining a positionof a grasped leaflet within the fixation device.
 12. The method of claim11, further comprising determining whether a leaflet is grasped betweenthe first arm and the first gripping element.